URL
https://opencores.org/ocsvn/openrisc/openrisc/trunk
Subversion Repositories openrisc
[/] [openrisc/] [tags/] [gdb/] [gdb-6.8/] [gdb-6.8.openrisc-2.1/] [gdb/] [doc/] [gdb.info-4] - Rev 754
Go to most recent revision | Compare with Previous | Blame | View Log
This is gdb.info, produced by makeinfo version 4.8 from
../.././gdb/doc/gdb.texinfo.
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb). The GNU debugger.
END-INFO-DIR-ENTRY
This file documents the GNU debugger GDB.
This is the Ninth Edition, of `Debugging with GDB: the GNU
Source-Level Debugger' for GDB Version 6.8.
Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."
File: gdb.info, Node: Bytecode Descriptions, Next: Using Agent Expressions, Prev: General Bytecode Design, Up: Agent Expressions
E.2 Bytecode Descriptions
=========================
Each bytecode description has the following form:
`add' (0x02): A B => A+B
Pop the top two stack items, A and B, as integers; push their sum,
as an integer.
In this example, `add' is the name of the bytecode, and `(0x02)' is
the one-byte value used to encode the bytecode, in hexadecimal. The
phrase "A B => A+B" shows the stack before and after the bytecode
executes. Beforehand, the stack must contain at least two values, A
and B; since the top of the stack is to the right, B is on the top of
the stack, and A is underneath it. After execution, the bytecode will
have popped A and B from the stack, and replaced them with a single
value, A+B. There may be other values on the stack below those shown,
but the bytecode affects only those shown.
Here is another example:
`const8' (0x22) N: => N
Push the 8-bit integer constant N on the stack, without sign
extension.
In this example, the bytecode `const8' takes an operand N directly
from the bytecode stream; the operand follows the `const8' bytecode
itself. We write any such operands immediately after the name of the
bytecode, before the colon, and describe the exact encoding of the
operand in the bytecode stream in the body of the bytecode description.
For the `const8' bytecode, there are no stack items given before the
=>; this simply means that the bytecode consumes no values from the
stack. If a bytecode consumes no values, or produces no values, the
list on either side of the => may be empty.
If a value is written as A, B, or N, then the bytecode treats it as
an integer. If a value is written is ADDR, then the bytecode treats it
as an address.
We do not fully describe the floating point operations here; although
this design can be extended in a clean way to handle floating point
values, they are not of immediate interest to the customer, so we avoid
describing them, to save time.
`float' (0x01): =>
Prefix for floating-point bytecodes. Not implemented yet.
`add' (0x02): A B => A+B
Pop two integers from the stack, and push their sum, as an integer.
`sub' (0x03): A B => A-B
Pop two integers from the stack, subtract the top value from the
next-to-top value, and push the difference.
`mul' (0x04): A B => A*B
Pop two integers from the stack, multiply them, and push the
product on the stack. Note that, when one multiplies two N-bit
numbers yielding another N-bit number, it is irrelevant whether the
numbers are signed or not; the results are the same.
`div_signed' (0x05): A B => A/B
Pop two signed integers from the stack; divide the next-to-top
value by the top value, and push the quotient. If the divisor is
zero, terminate with an error.
`div_unsigned' (0x06): A B => A/B
Pop two unsigned integers from the stack; divide the next-to-top
value by the top value, and push the quotient. If the divisor is
zero, terminate with an error.
`rem_signed' (0x07): A B => A MODULO B
Pop two signed integers from the stack; divide the next-to-top
value by the top value, and push the remainder. If the divisor is
zero, terminate with an error.
`rem_unsigned' (0x08): A B => A MODULO B
Pop two unsigned integers from the stack; divide the next-to-top
value by the top value, and push the remainder. If the divisor is
zero, terminate with an error.
`lsh' (0x09): A B => A<<B
Pop two integers from the stack; let A be the next-to-top value,
and B be the top value. Shift A left by B bits, and push the
result.
`rsh_signed' (0x0a): A B => `(signed)'A>>B
Pop two integers from the stack; let A be the next-to-top value,
and B be the top value. Shift A right by B bits, inserting copies
of the top bit at the high end, and push the result.
`rsh_unsigned' (0x0b): A B => A>>B
Pop two integers from the stack; let A be the next-to-top value,
and B be the top value. Shift A right by B bits, inserting zero
bits at the high end, and push the result.
`log_not' (0x0e): A => !A
Pop an integer from the stack; if it is zero, push the value one;
otherwise, push the value zero.
`bit_and' (0x0f): A B => A&B
Pop two integers from the stack, and push their bitwise `and'.
`bit_or' (0x10): A B => A|B
Pop two integers from the stack, and push their bitwise `or'.
`bit_xor' (0x11): A B => A^B
Pop two integers from the stack, and push their bitwise
exclusive-`or'.
`bit_not' (0x12): A => ~A
Pop an integer from the stack, and push its bitwise complement.
`equal' (0x13): A B => A=B
Pop two integers from the stack; if they are equal, push the value
one; otherwise, push the value zero.
`less_signed' (0x14): A B => A<B
Pop two signed integers from the stack; if the next-to-top value
is less than the top value, push the value one; otherwise, push
the value zero.
`less_unsigned' (0x15): A B => A<B
Pop two unsigned integers from the stack; if the next-to-top value
is less than the top value, push the value one; otherwise, push
the value zero.
`ext' (0x16) N: A => A, sign-extended from N bits
Pop an unsigned value from the stack; treating it as an N-bit
twos-complement value, extend it to full length. This means that
all bits to the left of bit N-1 (where the least significant bit
is bit 0) are set to the value of bit N-1. Note that N may be
larger than or equal to the width of the stack elements of the
bytecode engine; in this case, the bytecode should have no effect.
The number of source bits to preserve, N, is encoded as a single
byte unsigned integer following the `ext' bytecode.
`zero_ext' (0x2a) N: A => A, zero-extended from N bits
Pop an unsigned value from the stack; zero all but the bottom N
bits. This means that all bits to the left of bit N-1 (where the
least significant bit is bit 0) are set to the value of bit N-1.
The number of source bits to preserve, N, is encoded as a single
byte unsigned integer following the `zero_ext' bytecode.
`ref8' (0x17): ADDR => A
`ref16' (0x18): ADDR => A
`ref32' (0x19): ADDR => A
`ref64' (0x1a): ADDR => A
Pop an address ADDR from the stack. For bytecode `ref'N, fetch an
N-bit value from ADDR, using the natural target endianness. Push
the fetched value as an unsigned integer.
Note that ADDR may not be aligned in any particular way; the
`refN' bytecodes should operate correctly for any address.
If attempting to access memory at ADDR would cause a processor
exception of some sort, terminate with an error.
`ref_float' (0x1b): ADDR => D
`ref_double' (0x1c): ADDR => D
`ref_long_double' (0x1d): ADDR => D
`l_to_d' (0x1e): A => D
`d_to_l' (0x1f): D => A
Not implemented yet.
`dup' (0x28): A => A A
Push another copy of the stack's top element.
`swap' (0x2b): A B => B A
Exchange the top two items on the stack.
`pop' (0x29): A =>
Discard the top value on the stack.
`if_goto' (0x20) OFFSET: A =>
Pop an integer off the stack; if it is non-zero, branch to the
given offset in the bytecode string. Otherwise, continue to the
next instruction in the bytecode stream. In other words, if A is
non-zero, set the `pc' register to `start' + OFFSET. Thus, an
offset of zero denotes the beginning of the expression.
The OFFSET is stored as a sixteen-bit unsigned value, stored
immediately following the `if_goto' bytecode. It is always stored
most significant byte first, regardless of the target's normal
endianness. The offset is not guaranteed to fall at any particular
alignment within the bytecode stream; thus, on machines where
fetching a 16-bit on an unaligned address raises an exception, you
should fetch the offset one byte at a time.
`goto' (0x21) OFFSET: =>
Branch unconditionally to OFFSET; in other words, set the `pc'
register to `start' + OFFSET.
The offset is stored in the same way as for the `if_goto' bytecode.
`const8' (0x22) N: => N
`const16' (0x23) N: => N
`const32' (0x24) N: => N
`const64' (0x25) N: => N
Push the integer constant N on the stack, without sign extension.
To produce a small negative value, push a small twos-complement
value, and then sign-extend it using the `ext' bytecode.
The constant N is stored in the appropriate number of bytes
following the `const'B bytecode. The constant N is always stored
most significant byte first, regardless of the target's normal
endianness. The constant is not guaranteed to fall at any
particular alignment within the bytecode stream; thus, on machines
where fetching a 16-bit on an unaligned address raises an
exception, you should fetch N one byte at a time.
`reg' (0x26) N: => A
Push the value of register number N, without sign extension. The
registers are numbered following GDB's conventions.
The register number N is encoded as a 16-bit unsigned integer
immediately following the `reg' bytecode. It is always stored most
significant byte first, regardless of the target's normal
endianness. The register number is not guaranteed to fall at any
particular alignment within the bytecode stream; thus, on machines
where fetching a 16-bit on an unaligned address raises an
exception, you should fetch the register number one byte at a time.
`trace' (0x0c): ADDR SIZE =>
Record the contents of the SIZE bytes at ADDR in a trace buffer,
for later retrieval by GDB.
`trace_quick' (0x0d) SIZE: ADDR => ADDR
Record the contents of the SIZE bytes at ADDR in a trace buffer,
for later retrieval by GDB. SIZE is a single byte unsigned
integer following the `trace' opcode.
This bytecode is equivalent to the sequence `dup const8 SIZE
trace', but we provide it anyway to save space in bytecode strings.
`trace16' (0x30) SIZE: ADDR => ADDR
Identical to trace_quick, except that SIZE is a 16-bit big-endian
unsigned integer, not a single byte. This should probably have
been named `trace_quick16', for consistency.
`end' (0x27): =>
Stop executing bytecode; the result should be the top element of
the stack. If the purpose of the expression was to compute an
lvalue or a range of memory, then the next-to-top of the stack is
the lvalue's address, and the top of the stack is the lvalue's
size, in bytes.
File: gdb.info, Node: Using Agent Expressions, Next: Varying Target Capabilities, Prev: Bytecode Descriptions, Up: Agent Expressions
E.3 Using Agent Expressions
===========================
Here is a sketch of a full non-stop debugging cycle, showing how agent
expressions fit into the process.
* The user selects trace points in the program's code at which GDB
should collect data.
* The user specifies expressions to evaluate at each trace point.
These expressions may denote objects in memory, in which case
those objects' contents are recorded as the program runs, or
computed values, in which case the values themselves are recorded.
* GDB transmits the tracepoints and their associated expressions to
the GDB agent, running on the debugging target.
* The agent arranges to be notified when a trace point is hit. Note
that, on some systems, the target operating system is completely
responsible for collecting the data; see *Note Tracing on
Symmetrix::.
* When execution on the target reaches a trace point, the agent
evaluates the expressions associated with that trace point, and
records the resulting values and memory ranges.
* Later, when the user selects a given trace event and inspects the
objects and expression values recorded, GDB talks to the agent to
retrieve recorded data as necessary to meet the user's requests.
If the user asks to see an object whose contents have not been
recorded, GDB reports an error.
File: gdb.info, Node: Varying Target Capabilities, Next: Tracing on Symmetrix, Prev: Using Agent Expressions, Up: Agent Expressions
E.4 Varying Target Capabilities
===============================
Some targets don't support floating-point, and some would rather not
have to deal with `long long' operations. Also, different targets will
have different stack sizes, and different bytecode buffer lengths.
Thus, GDB needs a way to ask the target about itself. We haven't
worked out the details yet, but in general, GDB should be able to send
the target a packet asking it to describe itself. The reply should be a
packet whose length is explicit, so we can add new information to the
packet in future revisions of the agent, without confusing old versions
of GDB, and it should contain a version number. It should contain at
least the following information:
* whether floating point is supported
* whether `long long' is supported
* maximum acceptable size of bytecode stack
* maximum acceptable length of bytecode expressions
* which registers are actually available for collection
* whether the target supports disabled tracepoints
File: gdb.info, Node: Tracing on Symmetrix, Next: Rationale, Prev: Varying Target Capabilities, Up: Agent Expressions
E.5 Tracing on Symmetrix
========================
This section documents the API used by the GDB agent to collect data on
Symmetrix systems.
Cygnus originally implemented these tracing features to help EMC
Corporation debug their Symmetrix high-availability disk drives. The
Symmetrix application code already includes substantial tracing
facilities; the GDB agent for the Symmetrix system uses those facilities
for its own data collection, via the API described here.
-- Function: DTC_RESPONSE adbg_find_memory_in_frame (FRAME_DEF *FRAME,
char *ADDRESS, char **BUFFER, unsigned int *SIZE)
Search the trace frame FRAME for memory saved from ADDRESS. If
the memory is available, provide the address of the buffer holding
it; otherwise, provide the address of the next saved area.
* If the memory at ADDRESS was saved in FRAME, set `*BUFFER' to
point to the buffer in which that memory was saved, set
`*SIZE' to the number of bytes from ADDRESS that are saved at
`*BUFFER', and return `OK_TARGET_RESPONSE'. (Clearly, in
this case, the function will always set `*SIZE' to a value
greater than zero.)
* If FRAME does not record any memory at ADDRESS, set `*SIZE'
to the distance from ADDRESS to the start of the saved region
with the lowest address higher than ADDRESS. If there is no
memory saved from any higher address, set `*SIZE' to zero.
Return `NOT_FOUND_TARGET_RESPONSE'.
These two possibilities allow the caller to either retrieve the
data, or walk the address space to the next saved area.
This function allows the GDB agent to map the regions of memory
saved in a particular frame, and retrieve their contents efficiently.
This function also provides a clean interface between the GDB agent
and the Symmetrix tracing structures, making it easier to adapt the GDB
agent to future versions of the Symmetrix system, and vice versa. This
function searches all data saved in FRAME, whether the data is there at
the request of a bytecode expression, or because it falls in one of the
format's memory ranges, or because it was saved from the top of the
stack. EMC can arbitrarily change and enhance the tracing mechanism,
but as long as this function works properly, all collected memory is
visible to GDB.
The function itself is straightforward to implement. A single pass
over the trace frame's stack area, memory ranges, and expression blocks
can yield the address of the buffer (if the requested address was
saved), and also note the address of the next higher range of memory,
to be returned when the search fails.
As an example, suppose the trace frame `f' has saved sixteen bytes
from address `0x8000' in a buffer at `0x1000', and thirty-two bytes
from address `0xc000' in a buffer at `0x1010'. Here are some sample
calls, and the effect each would have:
`adbg_find_memory_in_frame (f, (char*) 0x8000, &buffer, &size)'
This would set `buffer' to `0x1000', set `size' to sixteen, and
return `OK_TARGET_RESPONSE', since `f' saves sixteen bytes from
`0x8000' at `0x1000'.
`adbg_find_memory_in_frame (f, (char *) 0x8004, &buffer, &size)'
This would set `buffer' to `0x1004', set `size' to twelve, and
return `OK_TARGET_RESPONSE', since `f' saves the twelve bytes from
`0x8004' starting four bytes into the buffer at `0x1000'. This
shows that request addresses may fall in the middle of saved
areas; the function should return the address and size of the
remainder of the buffer.
`adbg_find_memory_in_frame (f, (char *) 0x8100, &buffer, &size)'
This would set `size' to `0x3f00' and return
`NOT_FOUND_TARGET_RESPONSE', since there is no memory saved in `f'
from the address `0x8100', and the next memory available is at
`0x8100 + 0x3f00', or `0xc000'. This shows that request addresses
may fall outside of all saved memory ranges; the function should
indicate the next saved area, if any.
`adbg_find_memory_in_frame (f, (char *) 0x7000, &buffer, &size)'
This would set `size' to `0x1000' and return
`NOT_FOUND_TARGET_RESPONSE', since the next saved memory is at
`0x7000 + 0x1000', or `0x8000'.
`adbg_find_memory_in_frame (f, (char *) 0xf000, &buffer, &size)'
This would set `size' to zero, and return
`NOT_FOUND_TARGET_RESPONSE'. This shows how the function tells the
caller that no further memory ranges have been saved.
As another example, here is a function which will print out the
addresses of all memory saved in the trace frame `frame' on the
Symmetrix INLINES console:
void
print_frame_addresses (FRAME_DEF *frame)
{
char *addr;
char *buffer;
unsigned long size;
addr = 0;
for (;;)
{
/* Either find out how much memory we have here, or discover
where the next saved region is. */
if (adbg_find_memory_in_frame (frame, addr, &buffer, &size)
== OK_TARGET_RESPONSE)
printp ("saved %x to %x\n", addr, addr + size);
if (size == 0)
break;
addr += size;
}
}
Note that there is not necessarily any connection between the order
in which the data is saved in the trace frame, and the order in which
`adbg_find_memory_in_frame' will return those memory ranges. The code
above will always print the saved memory regions in order of increasing
address, while the underlying frame structure might store the data in a
random order.
[[This section should cover the rest of the Symmetrix functions the
stub relies upon, too.]]
File: gdb.info, Node: Rationale, Prev: Tracing on Symmetrix, Up: Agent Expressions
E.6 Rationale
=============
Some of the design decisions apparent above are arguable.
What about stack overflow/underflow?
GDB should be able to query the target to discover its stack size.
Given that information, GDB can determine at translation time
whether a given expression will overflow the stack. But this spec
isn't about what kinds of error-checking GDB ought to do.
Why are you doing everything in LONGEST?
Speed isn't important, but agent code size is; using LONGEST
brings in a bunch of support code to do things like division, etc.
So this is a serious concern.
First, note that you don't need different bytecodes for different
operand sizes. You can generate code without _knowing_ how big the
stack elements actually are on the target. If the target only
supports 32-bit ints, and you don't send any 64-bit bytecodes,
everything just works. The observation here is that the MIPS and
the Alpha have only fixed-size registers, and you can still get
C's semantics even though most instructions only operate on
full-sized words. You just need to make sure everything is
properly sign-extended at the right times. So there is no need
for 32- and 64-bit variants of the bytecodes. Just implement
everything using the largest size you support.
GDB should certainly check to see what sizes the target supports,
so the user can get an error earlier, rather than later. But this
information is not necessary for correctness.
Why don't you have `>' or `<=' operators?
I want to keep the interpreter small, and we don't need them. We
can combine the `less_' opcodes with `log_not', and swap the order
of the operands, yielding all four asymmetrical comparison
operators. For example, `(x <= y)' is `! (x > y)', which is `! (y
< x)'.
Why do you have `log_not'?
Why do you have `ext'?
Why do you have `zero_ext'?
These are all easily synthesized from other instructions, but I
expect them to be used frequently, and they're simple, so I
include them to keep bytecode strings short.
`log_not' is equivalent to `const8 0 equal'; it's used in half the
relational operators.
`ext N' is equivalent to `const8 S-N lsh const8 S-N rsh_signed',
where S is the size of the stack elements; it follows `refM' and
REG bytecodes when the value should be signed. See the next
bulleted item.
`zero_ext N' is equivalent to `constM MASK log_and'; it's used
whenever we push the value of a register, because we can't assume
the upper bits of the register aren't garbage.
Why not have sign-extending variants of the `ref' operators?
Because that would double the number of `ref' operators, and we
need the `ext' bytecode anyway for accessing bitfields.
Why not have constant-address variants of the `ref' operators?
Because that would double the number of `ref' operators again, and
`const32 ADDRESS ref32' is only one byte longer.
Why do the `refN' operators have to support unaligned fetches?
GDB will generate bytecode that fetches multi-byte values at
unaligned addresses whenever the executable's debugging
information tells it to. Furthermore, GDB does not know the value
the pointer will have when GDB generates the bytecode, so it
cannot determine whether a particular fetch will be aligned or not.
In particular, structure bitfields may be several bytes long, but
follow no alignment rules; members of packed structures are not
necessarily aligned either.
In general, there are many cases where unaligned references occur
in correct C code, either at the programmer's explicit request, or
at the compiler's discretion. Thus, it is simpler to make the GDB
agent bytecodes work correctly in all circumstances than to make
GDB guess in each case whether the compiler did the usual thing.
Why are there no side-effecting operators?
Because our current client doesn't want them? That's a cheap
answer. I think the real answer is that I'm afraid of
implementing function calls. We should re-visit this issue after
the present contract is delivered.
Why aren't the `goto' ops PC-relative?
The interpreter has the base address around anyway for PC bounds
checking, and it seemed simpler.
Why is there only one offset size for the `goto' ops?
Offsets are currently sixteen bits. I'm not happy with this
situation either:
Suppose we have multiple branch ops with different offset sizes.
As I generate code left-to-right, all my jumps are forward jumps
(there are no loops in expressions), so I never know the target
when I emit the jump opcode. Thus, I have to either always assume
the largest offset size, or do jump relaxation on the code after I
generate it, which seems like a big waste of time.
I can imagine a reasonable expression being longer than 256 bytes.
I can't imagine one being longer than 64k. Thus, we need 16-bit
offsets. This kind of reasoning is so bogus, but relaxation is
pathetic.
The other approach would be to generate code right-to-left. Then
I'd always know my offset size. That might be fun.
Where is the function call bytecode?
When we add side-effects, we should add this.
Why does the `reg' bytecode take a 16-bit register number?
Intel's IA-64 architecture has 128 general-purpose registers, and
128 floating-point registers, and I'm sure it has some random
control registers.
Why do we need `trace' and `trace_quick'?
Because GDB needs to record all the memory contents and registers
an expression touches. If the user wants to evaluate an expression
`x->y->z', the agent must record the values of `x' and `x->y' as
well as the value of `x->y->z'.
Don't the `trace' bytecodes make the interpreter less general?
They do mean that the interpreter contains special-purpose code,
but that doesn't mean the interpreter can only be used for that
purpose. If an expression doesn't use the `trace' bytecodes, they
don't get in its way.
Why doesn't `trace_quick' consume its arguments the way everything else does?
In general, you do want your operators to consume their arguments;
it's consistent, and generally reduces the amount of stack
rearrangement necessary. However, `trace_quick' is a kludge to
save space; it only exists so we needn't write `dup const8 SIZE
trace' before every memory reference. Therefore, it's okay for it
not to consume its arguments; it's meant for a specific context in
which we know exactly what it should do with the stack. If we're
going to have a kludge, it should be an effective kludge.
Why does `trace16' exist?
That opcode was added by the customer that contracted Cygnus for
the data tracing work. I personally think it is unnecessary;
objects that large will be quite rare, so it is okay to use `dup
const16 SIZE trace' in those cases.
Whatever we decide to do with `trace16', we should at least leave
opcode 0x30 reserved, to remain compatible with the customer who
added it.
File: gdb.info, Node: Target Descriptions, Next: Copying, Prev: Agent Expressions, Up: Top
Appendix F Target Descriptions
******************************
*Warning:* target descriptions are still under active development, and
the contents and format may change between GDB releases. The format is
expected to stabilize in the future.
One of the challenges of using GDB to debug embedded systems is that
there are so many minor variants of each processor architecture in use.
It is common practice for vendors to start with a standard processor
core -- ARM, PowerPC, or MIPS, for example -- and then make changes to
adapt it to a particular market niche. Some architectures have
hundreds of variants, available from dozens of vendors. This leads to
a number of problems:
* With so many different customized processors, it is difficult for
the GDB maintainers to keep up with the changes.
* Since individual variants may have short lifetimes or limited
audiences, it may not be worthwhile to carry information about
every variant in the GDB source tree.
* When GDB does support the architecture of the embedded system at
hand, the task of finding the correct architecture name to give the
`set architecture' command can be error-prone.
To address these problems, the GDB remote protocol allows a target
system to not only identify itself to GDB, but to actually describe its
own features. This lets GDB support processor variants it has never
seen before -- to the extent that the descriptions are accurate, and
that GDB understands them.
GDB must be linked with the Expat library to support XML target
descriptions. *Note Expat::.
* Menu:
* Retrieving Descriptions:: How descriptions are fetched from a target.
* Target Description Format:: The contents of a target description.
* Predefined Target Types:: Standard types available for target
descriptions.
* Standard Target Features:: Features GDB knows about.
File: gdb.info, Node: Retrieving Descriptions, Next: Target Description Format, Up: Target Descriptions
F.1 Retrieving Descriptions
===========================
Target descriptions can be read from the target automatically, or
specified by the user manually. The default behavior is to read the
description from the target. GDB retrieves it via the remote protocol
using `qXfer' requests (*note qXfer: General Query Packets.). The
ANNEX in the `qXfer' packet will be `target.xml'. The contents of the
`target.xml' annex are an XML document, of the form described in *Note
Target Description Format::.
Alternatively, you can specify a file to read for the target
description. If a file is set, the target will not be queried. The
commands to specify a file are:
`set tdesc filename PATH'
Read the target description from PATH.
`unset tdesc filename'
Do not read the XML target description from a file. GDB will use
the description supplied by the current target.
`show tdesc filename'
Show the filename to read for a target description, if any.
File: gdb.info, Node: Target Description Format, Next: Predefined Target Types, Prev: Retrieving Descriptions, Up: Target Descriptions
F.2 Target Description Format
=============================
A target description annex is an XML (http://www.w3.org/XML/) document
which complies with the Document Type Definition provided in the GDB
sources in `gdb/features/gdb-target.dtd'. This means you can use
generally available tools like `xmllint' to check that your feature
descriptions are well-formed and valid. However, to help people
unfamiliar with XML write descriptions for their targets, we also
describe the grammar here.
Target descriptions can identify the architecture of the remote
target and (for some architectures) provide information about custom
register sets. GDB can use this information to autoconfigure for your
target, or to warn you if you connect to an unsupported target.
Here is a simple target description:
<target version="1.0">
<architecture>i386:x86-64</architecture>
</target>
This minimal description only says that the target uses the x86-64
architecture.
A target description has the following overall form, with [ ] marking
optional elements and ... marking repeatable elements. The elements
are explained further below.
<?xml version="1.0"?>
<!DOCTYPE target SYSTEM "gdb-target.dtd">
<target version="1.0">
[ARCHITECTURE]
[FEATURE...]
</target>
The description is generally insensitive to whitespace and line breaks,
under the usual common-sense rules. The XML version declaration and
document type declaration can generally be omitted (GDB does not
require them), but specifying them may be useful for XML validation
tools. The `version' attribute for `<target>' may also be omitted, but
we recommend including it; if future versions of GDB use an incompatible
revision of `gdb-target.dtd', they will detect and report the version
mismatch.
F.2.1 Inclusion
---------------
It can sometimes be valuable to split a target description up into
several different annexes, either for organizational purposes, or to
share files between different possible target descriptions. You can
divide a description into multiple files by replacing any element of
the target description with an inclusion directive of the form:
<xi:include href="DOCUMENT"/>
When GDB encounters an element of this form, it will retrieve the named
XML DOCUMENT, and replace the inclusion directive with the contents of
that document. If the current description was read using `qXfer', then
so will be the included document; DOCUMENT will be interpreted as the
name of an annex. If the current description was read from a file, GDB
will look for DOCUMENT as a file in the same directory where it found
the original description.
F.2.2 Architecture
------------------
An `<architecture>' element has this form:
<architecture>ARCH</architecture>
ARCH is an architecture name from the same selection accepted by
`set architecture' (*note Specifying a Debugging Target: Targets.).
F.2.3 Features
--------------
Each `<feature>' describes some logical portion of the target system.
Features are currently used to describe available CPU registers and the
types of their contents. A `<feature>' element has this form:
<feature name="NAME">
[TYPE...]
REG...
</feature>
Each feature's name should be unique within the description. The name
of a feature does not matter unless GDB has some special knowledge of
the contents of that feature; if it does, the feature should have its
standard name. *Note Standard Target Features::.
F.2.4 Types
-----------
Any register's value is a collection of bits which GDB must interpret.
The default interpretation is a two's complement integer, but other
types can be requested by name in the register description. Some
predefined types are provided by GDB (*note Predefined Target Types::),
and the description can define additional composite types.
Each type element must have an `id' attribute, which gives a unique
(within the containing `<feature>') name to the type. Types must be
defined before they are used.
Some targets offer vector registers, which can be treated as arrays
of scalar elements. These types are written as `<vector>' elements,
specifying the array element type, TYPE, and the number of elements,
COUNT:
<vector id="ID" type="TYPE" count="COUNT"/>
If a register's value is usefully viewed in multiple ways, define it
with a union type containing the useful representations. The `<union>'
element contains one or more `<field>' elements, each of which has a
NAME and a TYPE:
<union id="ID">
<field name="NAME" type="TYPE"/>
...
</union>
F.2.5 Registers
---------------
Each register is represented as an element with this form:
<reg name="NAME"
bitsize="SIZE"
[regnum="NUM"]
[save-restore="SAVE-RESTORE"]
[type="TYPE"]
[group="GROUP"]/>
The components are as follows:
NAME
The register's name; it must be unique within the target
description.
BITSIZE
The register's size, in bits.
REGNUM
The register's number. If omitted, a register's number is one
greater than that of the previous register (either in the current
feature or in a preceeding feature); the first register in the
target description defaults to zero. This register number is used
to read or write the register; e.g. it is used in the remote `p'
and `P' packets, and registers appear in the `g' and `G' packets
in order of increasing register number.
SAVE-RESTORE
Whether the register should be preserved across inferior function
calls; this must be either `yes' or `no'. The default is `yes',
which is appropriate for most registers except for some system
control registers; this is not related to the target's ABI.
TYPE
The type of the register. TYPE may be a predefined type, a type
defined in the current feature, or one of the special types `int'
and `float'. `int' is an integer type of the correct size for
BITSIZE, and `float' is a floating point type (in the
architecture's normal floating point format) of the correct size
for BITSIZE. The default is `int'.
GROUP
The register group to which this register belongs. GROUP must be
either `general', `float', or `vector'. If no GROUP is specified,
GDB will not display the register in `info registers'.
File: gdb.info, Node: Predefined Target Types, Next: Standard Target Features, Prev: Target Description Format, Up: Target Descriptions
F.3 Predefined Target Types
===========================
Type definitions in the self-description can build up composite types
from basic building blocks, but can not define fundamental types.
Instead, standard identifiers are provided by GDB for the fundamental
types. The currently supported types are:
`int8'
`int16'
`int32'
`int64'
`int128'
Signed integer types holding the specified number of bits.
`uint8'
`uint16'
`uint32'
`uint64'
`uint128'
Unsigned integer types holding the specified number of bits.
`code_ptr'
`data_ptr'
Pointers to unspecified code and data. The program counter and
any dedicated return address register may be marked as code
pointers; printing a code pointer converts it into a symbolic
address. The stack pointer and any dedicated address registers
may be marked as data pointers.
`ieee_single'
Single precision IEEE floating point.
`ieee_double'
Double precision IEEE floating point.
`arm_fpa_ext'
The 12-byte extended precision format used by ARM FPA registers.
File: gdb.info, Node: Standard Target Features, Prev: Predefined Target Types, Up: Target Descriptions
F.4 Standard Target Features
============================
A target description must contain either no registers or all the
target's registers. If the description contains no registers, then GDB
will assume a default register layout, selected based on the
architecture. If the description contains any registers, the default
layout will not be used; the standard registers must be described in
the target description, in such a way that GDB can recognize them.
This is accomplished by giving specific names to feature elements
which contain standard registers. GDB will look for features with
those names and verify that they contain the expected registers; if any
known feature is missing required registers, or if any required feature
is missing, GDB will reject the target description. You can add
additional registers to any of the standard features -- GDB will
display them just as if they were added to an unrecognized feature.
This section lists the known features and their expected contents.
Sample XML documents for these features are included in the GDB source
tree, in the directory `gdb/features'.
Names recognized by GDB should include the name of the company or
organization which selected the name, and the overall architecture to
which the feature applies; so e.g. the feature containing ARM core
registers is named `org.gnu.gdb.arm.core'.
The names of registers are not case sensitive for the purpose of
recognizing standard features, but GDB will only display registers
using the capitalization used in the description.
* Menu:
* ARM Features::
* MIPS Features::
* M68K Features::
* PowerPC Features::
File: gdb.info, Node: ARM Features, Next: MIPS Features, Up: Standard Target Features
F.4.1 ARM Features
------------------
The `org.gnu.gdb.arm.core' feature is required for ARM targets. It
should contain registers `r0' through `r13', `sp', `lr', `pc', and
`cpsr'.
The `org.gnu.gdb.arm.fpa' feature is optional. If present, it
should contain registers `f0' through `f7' and `fps'.
The `org.gnu.gdb.xscale.iwmmxt' feature is optional. If present, it
should contain at least registers `wR0' through `wR15' and `wCGR0'
through `wCGR3'. The `wCID', `wCon', `wCSSF', and `wCASF' registers
are optional.
File: gdb.info, Node: MIPS Features, Next: M68K Features, Prev: ARM Features, Up: Standard Target Features
F.4.2 MIPS Features
-------------------
The `org.gnu.gdb.mips.cpu' feature is required for MIPS targets. It
should contain registers `r0' through `r31', `lo', `hi', and `pc'.
They may be 32-bit or 64-bit depending on the target.
The `org.gnu.gdb.mips.cp0' feature is also required. It should
contain at least the `status', `badvaddr', and `cause' registers. They
may be 32-bit or 64-bit depending on the target.
The `org.gnu.gdb.mips.fpu' feature is currently required, though it
may be optional in a future version of GDB. It should contain
registers `f0' through `f31', `fcsr', and `fir'. They may be 32-bit or
64-bit depending on the target.
The `org.gnu.gdb.mips.linux' feature is optional. It should contain
a single register, `restart', which is used by the Linux kernel to
control restartable syscalls.
File: gdb.info, Node: M68K Features, Next: PowerPC Features, Prev: MIPS Features, Up: Standard Target Features
F.4.3 M68K Features
-------------------
``org.gnu.gdb.m68k.core''
``org.gnu.gdb.coldfire.core''
``org.gnu.gdb.fido.core''
One of those features must be always present. The feature that is
present determines which flavor of m86k is used. The feature that
is present should contain registers `d0' through `d7', `a0'
through `a5', `fp', `sp', `ps' and `pc'.
``org.gnu.gdb.coldfire.fp''
This feature is optional. If present, it should contain registers
`fp0' through `fp7', `fpcontrol', `fpstatus' and `fpiaddr'.
File: gdb.info, Node: PowerPC Features, Prev: M68K Features, Up: Standard Target Features
F.4.4 PowerPC Features
----------------------
The `org.gnu.gdb.power.core' feature is required for PowerPC targets.
It should contain registers `r0' through `r31', `pc', `msr', `cr',
`lr', `ctr', and `xer'. They may be 32-bit or 64-bit depending on the
target.
The `org.gnu.gdb.power.fpu' feature is optional. It should contain
registers `f0' through `f31' and `fpscr'.
The `org.gnu.gdb.power.altivec' feature is optional. It should
contain registers `vr0' through `vr31', `vscr', and `vrsave'.
The `org.gnu.gdb.power.spe' feature is optional. It should contain
registers `ev0h' through `ev31h', `acc', and `spefscr'. SPE targets
should provide 32-bit registers in `org.gnu.gdb.power.core' and provide
the upper halves in `ev0h' through `ev31h'. GDB will combine these to
present registers `ev0' through `ev31' to the user.
File: gdb.info, Node: Copying, Next: GNU Free Documentation License, Prev: Target Descriptions, Up: Top
Appendix G GNU GENERAL PUBLIC LICENSE
*************************************
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
========
The licenses for most software are designed to take away your freedom
to share and change it. By contrast, the GNU General Public License is
intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it in
new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software,
and (2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
modification follow.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains a
notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program",
below, refers to any such program or work, and a "work based on
the Program" means either the Program or any derivative work under
copyright law: that is to say, a work containing the Program or a
portion of it, either verbatim or with modifications and/or
translated into another language. (Hereinafter, translation is
included without limitation in the term "modification".) Each
licensee is addressed as "you".
Activities other than copying, distribution and modification are
not covered by this License; they are outside its scope. The act
of running the Program is not restricted, and the output from the
Program is covered only if its contents constitute a work based on
the Program (independent of having been made by running the
Program). Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any
warranty; and give any other recipients of the Program a copy of
this License along with the Program.
You may charge a fee for the physical act of transferring a copy,
and you may at your option offer warranty protection in exchange
for a fee.
2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
a. You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
b. You must cause any work that you distribute or publish, that
in whole or in part contains or is derived from the Program
or any part thereof, to be licensed as a whole at no charge
to all third parties under the terms of this License.
c. If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display
an announcement including an appropriate copyright notice and
a notice that there is no warranty (or else, saying that you
provide a warranty) and that users may redistribute the
program under these conditions, and telling the user how to
view a copy of this License. (Exception: if the Program
itself is interactive but does not normally print such an
announcement, your work based on the Program is not required
to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the
Program, and can be reasonably considered independent and separate
works in themselves, then this License, and its terms, do not
apply to those sections when you distribute them as separate
works. But when you distribute the same sections as part of a
whole which is a work based on the Program, the distribution of
the whole must be on the terms of this License, whose permissions
for other licensees extend to the entire whole, and thus to each
and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or
contest your rights to work written entirely by you; rather, the
intent is to exercise the right to control the distribution of
derivative or collective works based on the Program.
In addition, mere aggregation of another work not based on the
Program with the Program (or with a work based on the Program) on
a volume of a storage or distribution medium does not bring the
other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms
of Sections 1 and 2 above provided that you also do one of the
following:
a. Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of
Sections 1 and 2 above on a medium customarily used for
software interchange; or,
b. Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a
medium customarily used for software interchange; or,
c. Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with
such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete
source code means all the source code for all modules it contains,
plus any associated interface definition files, plus the scripts
used to control compilation and installation of the executable.
However, as a special exception, the source code distributed need
not include anything that is normally distributed (in either
source or binary form) with the major components (compiler,
kernel, and so on) of the operating system on which the executable
runs, unless that component itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this
License. However, parties who have received copies, or rights,
from you under this License will not have their licenses
terminated so long as such parties remain in full compliance.
5. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify
or distribute the Program or its derivative works. These actions
are prohibited by law if you do not accept this License.
Therefore, by modifying or distributing the Program (or any work
based on the Program), you indicate your acceptance of this
License to do so, and all its terms and conditions for copying,
distributing or modifying the Program or works based on it.
6. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program
subject to these terms and conditions. You may not impose any
further restrictions on the recipients' exercise of the rights
granted herein. You are not responsible for enforcing compliance
by third parties to this License.
7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent
issues), conditions are imposed on you (whether by court order,
agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this
License. If you cannot distribute so as to satisfy simultaneously
your obligations under this License and any other pertinent
obligations, then as a consequence you may not distribute the
Program at all. For example, if a patent license would not permit
royalty-free redistribution of the Program by all those who
receive copies directly or indirectly through you, then the only
way you could satisfy both it and this License would be to refrain
entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable
under any particular circumstance, the balance of the section is
intended to apply and the section as a whole is intended to apply
in other circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of
any such claims; this section has the sole purpose of protecting
the integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is
willing to distribute software through any other system and a
licensee cannot impose that choice.
This section is intended to make thoroughly clear what is believed
to be a consequence of the rest of this License.
8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces,
the original copyright holder who places the Program under this
License may add an explicit geographical distribution limitation
excluding those countries, so that distribution is permitted only
in or among countries not thus excluded. In such case, this
License incorporates the limitation as if written in the body of
this License.
9. The Free Software Foundation may publish revised and/or new
versions of the General Public License from time to time. Such
new versions will be similar in spirit to the present version, but
may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies a version number of this License which applies
to it and "any later version", you have the option of following
the terms and conditions either of that version or of any later
version published by the Free Software Foundation. If the Program
does not specify a version number of this License, you may choose
any version ever published by the Free Software Foundation.
10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the
author to ask for permission. For software which is copyrighted
by the Free Software Foundation, write to the Free Software
Foundation; we sometimes make exceptions for this. Our decision
will be guided by the two goals of preserving the free status of
all derivatives of our free software and of promoting the sharing
and reuse of software generally.
NO WARRANTY
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR CORRECTION.
12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
=============================================
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
Copyright (C) YEAR NAME OF AUTHOR
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
Also add information on how to contact you by electronic and paper
mail.
If the program is interactive, make it output a short notice like
this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the
appropriate parts of the General Public License. Of course, the
commands you use may be called something other than `show w' and `show
c'; they could even be mouse-clicks or menu items--whatever suits your
program.
You should also get your employer (if you work as a programmer) or
your school, if any, to sign a "copyright disclaimer" for the program,
if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
SIGNATURE OF TY COON, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Library General Public License instead of this License.
File: gdb.info, Node: GNU Free Documentation License, Next: Index, Prev: Copying, Up: Top
Appendix H GNU Free Documentation License
*****************************************
Version 1.2, November 2002
Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book.
We recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it
can be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
of the public is a licensee, and is addressed as "you". You
accept the license if you copy, modify or distribute the work in a
way requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.) The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in
the notice that says that the Document is released under this
License. If a section does not fit the above definition of
Secondary then it is not allowed to be designated as Invariant.
The Document may contain zero Invariant Sections. If the Document
does not identify any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images
composed of pixels) generic paint programs or (for drawings) some
widely available drawing editor, and that is suitable for input to
text formatters or for automatic translation to a variety of
formats suitable for input to text formatters. A copy made in an
otherwise Transparent file format whose markup, or absence of
markup, has been arranged to thwart or discourage subsequent
modification by readers is not Transparent. An image format is
not Transparent if used for any substantial amount of text. A
copy that is not "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
SGML or XML using a publicly available DTD, and
standard-conforming simple HTML, PostScript or PDF designed for
human modification. Examples of transparent image formats include
PNG, XCF and JPG. Opaque formats include proprietary formats that
can be read and edited only by proprietary word processors, SGML or
XML for which the DTD and/or processing tools are not generally
available, and the machine-generated HTML, PostScript or PDF
produced by some word processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page. For
works in formats which do not have any title page as such, "Title
Page" means the text near the most prominent appearance of the
work's title, preceding the beginning of the body of the text.
A section "Entitled XYZ" means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language. (Here XYZ
stands for a specific section name mentioned below, such as
"Acknowledgements", "Dedications", "Endorsements", or "History".)
To "Preserve the Title" of such a section when you modify the
Document means that it remains a section "Entitled XYZ" according
to this definition.
The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document. These
Warranty Disclaimers are considered to be included by reference in
this License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and
has no effect on the meaning of this License.
2. VERBATIM COPYING
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
add no other conditions whatsoever to those of this License. You
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
distribute a large enough number of copies you must also follow
the conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document's license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
front cover must present the full title with all words of the
title equally prominent and visible. You may add other material
on the covers in addition. Copying with changes limited to the
covers, as long as they preserve the title of the Document and
satisfy these conditions, can be treated as verbatim copying in
other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.
If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a
machine-readable Transparent copy along with each Opaque copy, or
state in or with each Opaque copy a computer-network location from
which the general network-using public has access to download
using public-standard network protocols a complete Transparent
copy of the Document, free of added material. If you use the
latter option, you must take reasonably prudent steps, when you
begin distribution of Opaque copies in quantity, to ensure that
this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you
distribute an Opaque copy (directly or through your agents or
retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
the Document well before redistributing any large number of
copies, to give them a chance to provide you with an updated
version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with
the Modified Version filling the role of the Document, thus
licensing distribution and modification of the Modified Version to
whoever possesses a copy of it. In addition, you must do these
things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of
previous versions (which should, if there were any, be listed
in the History section of the Document). You may use the
same title as a previous version if the original publisher of
that version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
the Modified Version, together with at least five of the
principal authors of the Document (all of its principal
authors, if it has fewer than five), unless they release you
from this requirement.
C. State on the Title page the name of the publisher of the
Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified
Version under the terms of this License, in the form shown in
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document's
license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on
the Title Page. If there is no section Entitled "History" in
the Document, create one stating the title, year, authors,
and publisher of the Document as given on its Title Page,
then add an item describing the Modified Version as stated in
the previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in
the "History" section. You may omit a network location for a
work that was published at least four years before the
Document itself, or if the original publisher of the version
it refers to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
Preserve the Title of the section, and preserve in the
section all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section
titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option
designate some or all of these sections as invariant. To do this,
add their titles to the list of Invariant Sections in the Modified
Version's license notice. These titles must be distinct from any
other section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text
has been approved by an organization as the authoritative
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end
of the list of Cover Texts in the Modified Version. Only one
passage of Front-Cover Text and one of Back-Cover Text may be
added by (or through arrangements made by) any one entity. If the
Document already includes a cover text for the same cover,
previously added by you or by arrangement made by the same entity
you are acting on behalf of, you may not add another; but you may
replace the old one, on explicit permission from the previous
publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination
all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications". You
must delete all sections Entitled "Endorsements."
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the
documents in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow
this License in all other respects regarding verbatim copying of
that document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided for under this License. Any other
attempt to copy, modify, sublicense or distribute the Document is
void, and will automatically terminate your rights under this
License. However, parties who have received copies, or rights,
from you under this License will not have their licenses
terminated so long as such parties remain in full compliance.
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
`http://www.gnu.org/copyleft/'.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
Free Software Foundation.
H.1 ADDENDUM: How to use this License for your documents
========================================================
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.
File: gdb.info, Node: Index, Prev: GNU Free Documentation License, Up: Top
Index
*****