From: Dirk Behme <dirk.behme@googlemail.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: Single stepping MIPS in GDB
Date: Wed, 29 Mar 2006 10:08:43 +0200 [thread overview]
Message-ID: <442A408B.90702@gmail.com> (raw)
In-Reply-To: <4428267D.6030707@gmail.com>
Hi,
if nobody has an idea regarding this, any hint where to
search or how to debug this the best way?
What confuses me is that qemu.log correctly shows
pc=0x80010400 but qemu monitor register info and GDB show pc=0.
Thanks
Dirk
Dirk Behme wrote:
> Hi,
>
> now, after ARM, I try to debug some low level system init code on MIPS
> as well. For this, I use qemu-snapshot-2006-03-21_23 because this
> already includes little endian MIPS (--target-list=mipsel-softmmu). I
> can load my program to MIPS default start address 0x80010000, use
> mipsel-linux-gdb to attach to it and load symbols. Start address is set
> correctly. But seems that I have trouble single stepping (si). I would
> assume that with first si system should jump to 0x80010400 (please find
> some debug output below). Instead, PC is set to 0x0.
>
> If I start program with 'continue' in gdb, seems that program starts to
> run correctly. After stop at random location with ctrl-c in gdb, the
> following single steps seem to fail as well (please see below as well).
>
> Any hints what I'm making wrong here?
>
> Many thanks
>
> Dirk
>
> *1* Debug output for single step at startup. PC is set to 0x0 instead to
> next command at 0x80010400
>
> _start ()
> at uboot/u-boot-1.1.4/cpu/mips/start.S:43
> 43 RVECENT(reset,0) /* U-boot entry point */
> (gdb) p/x $pc
> $1 = 0x80010000
> (gdb) x/2i $pc
> 0x80010000 <_start>: b 0x80010400 <reset>
> 0x80010004 <_start+4>: nop
> (gdb) si
> 0x00000000 in ?? ()
> (gdb) p/x $pc
> $2 = 0x0
> (gdb)
>
> /tmp> cat qemu.log
> pc=0x80010000 HI=0x00000000 LO=0x00000000 ds 0002 00000000 0
> GPR00: r0 00000000 at 00000000 v0 00000000 v1 00000000
> GPR04: a0 00000000 a1 00000000 a2 00000000 a3 00000000
> GPR08: t0 00000000 t1 00000000 t2 00000000 t3 00000000
> GPR12: t4 00000000 t5 00000000 t6 00000000 t7 00000000
> GPR16: s0 00000000 s1 00000000 s2 00000000 s3 00000000
> GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
> GPR24: t8 00000000 t9 00000000 k0 00000000 k1 00000000
> GPR28: gp 00000000 sp 00000000 s8 00000000 ra 00000000
> CP0 Status 0x10400004 Cause 0x00000400 EPC 0x00000000
> Config0 0x80008090 Config1 0x1e190c8a LLAddr 0x00000000
> cpu_mips_handle_mmu_fault pc 80010000 ad 80010000 rw 2 is_user 0 smmu 1
> cpu_mips_handle_mmu_fault address=80010000 ret 0 physical 00010000 prot 3
> ------------------------------------------------
> pc=0x80010000 HI=0x00000000 LO=0x00000000 ds 0002 00000000 0
> GPR00: r0 00000000 at 00000000 v0 00000000 v1 00000000
> GPR04: a0 00000000 a1 00000000 a2 00000000 a3 00000000
> GPR08: t0 00000000 t1 00000000 t2 00000000 t3 00000000
> GPR12: t4 00000000 t5 00000000 t6 00000000 t7 00000000
> GPR16: s0 00000000 s1 00000000 s2 00000000 s3 00000000
> GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
> GPR24: t8 00000000 t9 00000000 k0 00000000 k1 00000000
> GPR28: gp 00000000 sp 00000000 s8 00000000 ra 00000000
> CP0 Status 0x10400004 Cause 0x00000400 EPC 0x00000000
> Config0 0x80008090 Config1 0x1e190c8a LLAddr 0x00000000
> IN:
> 0x80010000: b 0x80010400
> 0x80010004: nop
>
> OP:
> 0x0000: goto_tb0
> 0x0001: save_pc 0x80010400
> 0x0002: set_T0 0x829ce00
> 0x0003: exit_tb
> 0x0004: reset_T0
> 0x0005: exit_tb
> 0x0006: end
>
> ---------------- 2 00000002
> OUT: [size=24]
> 0x08a9ce00: jmp 0xa4ab0b4
> 0x08a9ce05: movl $0x80010400,0x80(%ebp)
> 0x08a9ce0f: mov $0x829ce00,%ebx
> 0x08a9ce14: ret
> 0x08a9ce15: xor %ebx,%ebx
> 0x08a9ce17: ret
>
> Trace 0x08a9ce00 [80010000]
> pc=0x80010400 HI=0x00000000 LO=0x00000000 ds 0002 00000000 0
> GPR00: r0 00000000 at 00000000 v0 00000000 v1 00000000
> GPR04: a0 00000000 a1 00000000 a2 00000000 a3 00000000
> GPR08: t0 00000000 t1 00000000 t2 00000000 t3 00000000
> GPR12: t4 00000000 t5 00000000 t6 00000000 t7 00000000
> GPR16: s0 00000000 s1 00000000 s2 00000000 s3 00000000
> GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
> GPR24: t8 00000000 t9 00000000 k0 00000000 k1 00000000
> GPR28: gp 00000000 sp 00000000 s8 00000000 ra 00000000
> CP0 Status 0x10400004 Cause 0x00000400 EPC 0x00000000
> Config0 0x80008090 Config1 0x1e190c8a LLAddr 0x00000000
> ------------------------------------------------
> pc=0x80010400 HI=0x00000000 LO=0x00000000 ds 0002 00000000 0
> GPR00: r0 00000000 at 00000000 v0 00000000 v1 00000000
> GPR04: a0 00000000 a1 00000000 a2 00000000 a3 00000000
> GPR08: t0 00000000 t1 00000000 t2 00000000 t3 00000000
> GPR12: t4 00000000 t5 00000000 t6 00000000 t7 00000000
> GPR16: s0 00000000 s1 00000000 s2 00000000 s3 00000000
> GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
> GPR24: t8 00000000 t9 00000000 k0 00000000 k1 00000000
> GPR28: gp 00000000 sp 00000000 s8 00000000 ra 00000000
> CP0 Status 0x10400004 Cause 0x00000400 EPC 0x00000000
> Config0 0x80008090 Config1 0x1e190c8a LLAddr 0x00000000
> IN:
>
> OP:
> 0x0000: save_pc 0x80010400
> 0x0001: debug
> 0x0002: end
>
> ---------------- 2 00000002
> OUT: [size=21]
> 0x08a9ce20: movl $0x80010400,0x80(%ebp)
> 0x08a9ce2a: push $0x10002
> 0x08a9ce2f: call 0x80866c0
> 0x08a9ce34: pop %eax
>
> Trace 0x08a9ce20 [80010400]
> search pc 1
> ------------------------------------------------
> pc=0x80010400 HI=0x00000000 LO=0x00000000 ds 0002 00000000 0
> GPR00: r0 00000000 at 00000000 v0 00000000 v1 00000000
> GPR04: a0 00000000 a1 00000000 a2 00000000 a3 00000000
> GPR08: t0 00000000 t1 00000000 t2 00000000 t3 00000000
> GPR12: t4 00000000 t5 00000000 t6 00000000 t7 00000000
> GPR16: s0 00000000 s1 00000000 s2 00000000 s3 00000000
> GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
> GPR24: t8 00000000 t9 00000000 k0 00000000 k1 00000000
> GPR28: gp 00000000 sp 00000000 s8 00000000 ra 00000000
> CP0 Status 0x10400004 Cause 0x00000400 EPC 0x00000000
> Config0 0x80008090 Config1 0x1e190c8a LLAddr 0x00000000
> IN:
>
> OP:
> 0x0000: save_pc 0x80010400
> 0x0001: debug
> 0x0002: end
>
> ---------------- 2 00000002
> /tmp >
>
> Debug output from debug enabled in gdbserver:
>
> command='m80010000,4'
> reply='ff000010'
> command='m80010004,4'
> reply='00000000'
> command='m80010000,4'
> reply='ff000010'
> command='m80010004,4'
> reply='00000000'
> command='m80010000,4'
> reply='ff000010'
> command='Z0,80010400,4'
> reply='OK'
> command='vCont?'
> reply=''
> command='Hc0'
> reply=''
> command='c'
> Foo #B ret: 0
> reply='S05'
> command='g'
> reply='0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040100000000000000000000000000004000000000000'
>
> command='z0,80010400,4'
> reply='OK'
> command='m0,4'
> reply='00000000'
> command='mfffffffc,4'
> reply='E14'
> command='m0,4'
> reply='00000000'
> command='mfffffffc,4'
> reply='E14'
> command='m0,4'
> reply='00000000'
> command='mfffffffc,4'
> reply='E14'
> command='m0,4'
> reply='00000000'
> command='mfffffffc,4'
> reply='E14'
> command='m0,4'
> reply='00000000'
> command='m4,4'
> reply='00000000'
>
> *2* Start program with 'continue', stop somewhere with ctrl-c, then
> single step:
>
> (gdb) p/x $pc
> $3 = 0x800108cc
> (gdb) si
> 143 2: sw zero, 0(a0)
> (gdb) si
> 143 2: sw zero, 0(a0)
> (gdb) si
> 143 2: sw zero, 0(a0)
> (gdb) p/x $pc
> $4 = 0x800108cc
> (gdb) x/3i $pc
> 0x800108cc <mips_cache_reset+28>: sw zero,0(a0)
> 0x800108d0 <mips_cache_reset+32>: sw zero,4(a0)
> 0x800108d4 <mips_cache_reset+36>: sw zero,8(a0)
> (gdb)
>
next prev parent reply other threads:[~2006-03-29 8:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-27 17:53 [Qemu-devel] Single stepping MIPS in GDB Dirk Behme
2006-03-29 8:08 ` Dirk Behme [this message]
2006-03-29 13:40 ` [Qemu-devel] " Dirk Behme
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