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NAME="RESOURCE-USAGE">RedBoot Resource Usage</H1
><P
> </P
><P
>RedBoot takes up both flash and RAM resources depending on its
startup mode and number of enabled features. There are also other
resources used by RedBoot, such as timers. Platform-specific resources
used by RedBoot are listed in the platform specific parts of this
manual.</P
><P
>Both flash and RAM resources used by RedBoot depend to some
degree on the features enabled in the RedBoot configuration. It is
possible to reduce in particular the RAM resources used by RedBoot by
removing features that are not needed. Flash resources can also be
reduced, but due to the granularity of the flash (the block sizes),
reductions in feature size do not always result in flash resource
savings.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN2631">Flash Resources</H2
><P
>On many platforms, a ROM mode RedBoot image resides in the first
flash sectors, working as the board's primary boot monitor. On these
platforms, it is also normal to reserve a similar amount of flash for
a secondary RAM mode image, which is used when updating the primary
ROM mode image.</P
><P
>On other platforms, a ROMRAM mode RedBoot image is used as the
primary boot monitor. On these platforms there is not normally
reserved space for a RAM mode RedBoot image, since the ROMRAM mode
RedBoot is capable of updating the primary boot monitor image.</P
><P
>Most platforms also contain a FIS directory (keeping track of
available flash space) and a RedBoot config block (containing RedBoot
board configuration data).</P
><P
>To see the amount of reserved flash memory, run the <B
CLASS="COMMAND"
>fis
list</B
> command:
<TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="SCREEN"
>RedBoot> <TT
CLASS="USERINPUT"
><B
>fis list</B
></TT
>
Name FLASH addr Mem addr Length Entry point
RedBoot 0x00000000 0x00000000 0x00020000 0x00000000
RedBoot[RAM] 0x00020000 0x06020000 0x00020000 0x060213C0
RedBoot config 0x0007F000 0x0007F000 0x00001000 0x00000000
FIS directory 0x00070000 0x00070000 0x0000F000 0x00000000</PRE
></TD
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><P
>To save flash resources, use a ROMRAM mode RedBoot, or if using
a ROM mode RedBoot, avoid reserving space for the RedBoot[RAM] image
(this is done by changing the RedBoot configuration) and download the
RAM mode RedBoot whenever it is needed. If the RedBoot image takes up
a fraction of an extra flash block, it may be possible to reduce the
image size enough to free this block by removing some features.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN2641">RAM Resources</H2
><P
>RedBoot reserves RAM space for its run-time data, and such
things as CPU exception/interrupt tables. It normally does so at the
bottom of the memory map. It may also reserve space at the top of the
memory map for configurable RedBoot features such as the net stack
and zlib decompression support.</P
><P
>To see the actual amount of reserved space, issue the
<B
CLASS="COMMAND"
>version</B
> command, which prints the RedBoot banner,
including the RAM usage:
<TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="SCREEN"
>RedBoot> <TT
CLASS="USERINPUT"
><B
>version</B
></TT
>
RedBoot(tm) bootstrap and debug environment [ROM]
Non-certified release, version UNKNOWN - built 13:31:57, May 17 2002
Platform: FooBar (SH 7615)
Copyright (C) 2000, 2001, 2002, Red Hat, Inc.
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>RAM: 0x06000000-0x06080000, 0x06012498-0x06061000 available</I
></SPAN
>
FLASH: 0x00000000 - 0x00080000, 8 blocks of 0x00010000 bytes each.</PRE
></TD
></TR
></TABLE
></P
><P
>To simplify operations that temporarily need data in free
memory, the limits of free RAM are also available as aliases (aligned
to the nearest kilo-byte limit). These are named
FREEMEMLO and
FREEMEMHI, and can
be used in commands like any user defined alias:
<TABLE
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BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="SCREEN"
>RedBoot> <TT
CLASS="USERINPUT"
><B
>load -r -b %{FREEMEMLO} file</B
></TT
>
Raw file loaded 0x06012800-0x06013e53, assumed entry at 0x06012800</PRE
></TD
></TR
></TABLE
>
<TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="SCREEN"
>RedBoot> <TT
CLASS="USERINPUT"
><B
>x -b %{FREEMEMHI}</B
></TT
>
06061000: 86 F5 EB D8 3D 11 51 F2 96 F4 B2 DC 76 76 8F 77 |....=.Q.....vv.w|
06061010: E6 55 DD DB F3 75 5D 15 E0 F3 FC D9 C8 73 1D DA |.U...u]......s..|</PRE
></TD
></TR
></TABLE
></P
><P
>To reduce RedBoot's RAM resource usage, use a ROM mode
RedBoot. The RedBoot features that use most RAM are the net stack, the
flash support and the gunzip support. These, and other features, can
be disabled to reduce the RAM footprint, but obviously at the cost of
lost functionality.</P
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