Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD plagnioj@jcrosoft.com --- diff with V1 remove unrelated changement doc/README.qemu_mips | 64 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 63 insertions(+), 1 deletions(-)
diff --git a/doc/README.qemu_mips b/doc/README.qemu_mips index c9ac3f3..472469f 100644 --- a/doc/README.qemu_mips +++ b/doc/README.qemu_mips @@ -1,7 +1,7 @@
Notes for the Qemu MIPS port
-Example usage: +I) Example usage:
# ln -s u-boot.bin mips_bios.bin start it: @@ -16,3 +16,65 @@ create image: # dd of=flash bs=1k conv=notrunc if=u-boot.bin start it: # qemu-system-mips -M mips -pflash flash -monitor null -nographic + +II) How to debug U-Boot + +In order to debug U-Boot you need to start qemu with gdb server support (-s) +and waiting the connection to start the CPU (-S) + +# qemu-system-mips -S -s -M mips -pflash flash -monitor null -nographic + +in an other console you start gdb + +1) Debugging of U-Boot Before Relocation + +Before relocation, the addresses in the ELF file can be used without any problems +buy connecting to the gdb server localhost:1234 + +# mipsel-unknown-linux-gnu-gdb u-boot +GNU gdb 6.6 +Copyright (C) 2006 Free Software Foundation, Inc. +GDB is free software, covered by the GNU General Public License, and you are +welcome to change it and/or distribute copies of it under certain conditions. +Type "show copying" to see the conditions. +There is absolutely no warranty for GDB. Type "show warranty" for details. +This GDB was configured as "--host=i486-linux-gnu --target=mipsel-unknown-linux-gnu"... +(gdb) target remote localhost:1234 +Remote debugging using localhost:1234 +_start () at start.S:64 +64 RVECENT(reset,0) /* U-boot entry point */ +Current language: auto; currently asm +(gdb) b board.c:289 +Breakpoint 1 at 0xbfc00cc8: file board.c, line 289. +(gdb) c +Continuing. + +Breakpoint 1, board_init_f (bootflag=<value optimized out>) at board.c:290 +290 relocate_code (addr_sp, id, addr); +Current language: auto; currently c +(gdb) p/x addr +$1 = 0x87fa0000 + +2) Debugging of U-Boot After Relocation + +For debugging U-Boot after relocation we need to know the address to which +U-Boot relocates itself to 0x87fa0000 by default. +And replace the symbol table to this offset. + +(gdb) symbol-file +Discard symbol table from `/private/u-boot-arm/u-boot'? (y or n) y +Error in re-setting breakpoint 1: +No symbol table is loaded. Use the "file" command. +No symbol file now. +(gdb) add-symbol-file u-boot 0x87fa0000 +add symbol table from file "u-boot" at + .text_addr = 0x87fa0000 +(y or n) y +Reading symbols from /private/u-boot-arm/u-boot...done. +Breakpoint 1 at 0x87fa0cc8: file board.c, line 289. +(gdb) c +Continuing. + +Program received signal SIGINT, Interrupt. +0xffffffff87fa0de4 in udelay (usec=<value optimized out>) at time.c:78 +78 while ((tmo - read_c0_count()) < 0x7fffffff)