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jeremybenn |
How to use SIS with GDB
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1. Building GDB with SIS
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To build GDB with the SIS/ERC32 simulator, configure with option
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'--target sparc-erc32-aout' and build as usual.
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2. Attaching the simulator
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To attach GDB to the simulator, use:
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target sim [options] [files]
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The following options are supported:
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-nfp Disable FPU. FPops will cause an FPU disabled trap.
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-freq Set the simulated "system clock" to MHz.
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-v Verbose mode.
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-nogdb Disable GDB breakpoint handling (see below)
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The listed [files] are expected to be in aout format and will be
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loaded in the simulator memory prior. This could be used to load
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a boot block at address 0x0 if the application is linked to run
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from RAM (0x2000000).
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To start debugging a program type 'load ' and debug as
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usual.
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The native simulator commands can be reached using the GDB 'sim'
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command:
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sim
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Direct simulator commands during a GDB session must be issued
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with care not to disturb GDB's operation ...
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For info on supported ERC32 functionality, see README.sis.
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3. Loading aout files
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The GDB load command loads an aout file into the simulator
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memory with the data section starting directly after the text
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section regardless of wich start address was specified for the data
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at link time! This means that your applications either has to include
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a routine that initialise the data segment at the proper address or
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link with the data placed directly after the text section.
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A copying routine is fairly simple, just copy all data between
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_etext and _data to a memory loaction starting at _environ. This
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should be done at the same time as the bss is cleared (in srt0.s).
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4. GDB breakpoint handling
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GDB inserts breakpoint in the form of the 'ta 1' instruction. The
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GDB-integrated simulator will therefore recognize the breakpoint
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instruction and return control to GDB. If the application uses
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'ta 1', the breakpoint detection can be disabled with the -nogdb
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switch. In this case however, GDB breakpoints will not work.
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Report problems to Jiri Gaisler ESA/ESTEC (jgais@wd.estec.esa.nl)
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