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      1 How to use SIS with GDB
      2 -----------------------
      3 
      4 1. Building GDB with SIS
      5 
      6 To build GDB with the SIS/ERC32 simulator, configure with option
      7 '--target sparc-erc32-aout' and build as usual.
      8 
      9 2. Attaching the simulator
     10 
     11 To attach GDB to the simulator, use:
     12 
     13 target sim [options] [files]
     14 
     15 The following options are supported:
     16 
     17  -nfp		Disable FPU. FPops will cause an FPU disabled trap.
     18 
     19  -freq <f>	Set the simulated "system clock" to <f> MHz.
     20 
     21  -v		Verbose mode.
     22 
     23  -nogdb		Disable GDB breakpoint handling (see below)
     24 
     25 The listed [files] are expected to be in aout format and will be
     26 loaded in the simulator memory prior. This could be used to load
     27 a boot block at address 0x0 if the application is linked to run
     28 from RAM (0x2000000).
     29 
     30 To start debugging a program type 'load <program>' and debug as
     31 usual. 
     32 
     33 The native simulator commands can be reached using the GDB 'sim'
     34 command:
     35 
     36 sim <sis_command>
     37 
     38 Direct simulator commands during a GDB session must be issued
     39 with care not to disturb GDB's operation ... 
     40 
     41 For info on supported ERC32 functionality, see README.sis.
     42 
     43 
     44 3. Loading aout files
     45 
     46 The GDB load command loads an aout file into the simulator
     47 memory with the data section starting directly after the text
     48 section regardless of wich start address was specified for the data
     49 at link time! This means that your applications either has to include
     50 a routine that initialise the data segment at the proper address or
     51 link with the data placed directly after the text section.
     52 
     53 A copying routine is fairly simple, just copy all data between
     54 _etext and _data to a memory loaction starting at _environ. This
     55 should be done at the same time as the bss is cleared (in srt0.s).
     56 
     57 
     58 4. GDB breakpoint handling
     59 
     60 GDB inserts breakpoint in the form of the 'ta 1' instruction. The
     61 GDB-integrated simulator will therefore recognize the breakpoint
     62 instruction and return control to GDB. If the application uses
     63 'ta 1', the breakpoint detection can be disabled with the -nogdb
     64 switch. In this case however, GDB breakpoints will not work.
     65 
     66 
     67 Report problems to Jiri Gaisler ESA/ESTEC (jgais (a] wd.estec.esa.nl)
     68