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)
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