Re: Looking for advise on debugging a non-boot kernel on qemu-system-sh4

[BALATON Zoltan]

Hello,

On Sat, 23 Oct 2021, John Paul Adrian Glaubitz wrote:
> On 10/23/21 03:07, BALATON Zoltan wrote:
> > > I can confirm that the default config works for me, too. Both with gcc-8 and 
> > > gcc-11.
> >
> > OK with your config I can reproduce the problem too but the kernel with that 
> > config
> > is 177MB and the r2d board has 64MB RAM so this can't work that way. Then it's 
> > likely
> > not a but but a too big kernel.
>
> You either need to strip the kernel with "strip vmlinux" or use the image from 
> arch/sh/
> boot/zImage.

I've actually used that kernel but looked at the wrong uncompressed size, 
it's indeed just 9.2MB when stripped so that should work. I was trying to 
debug further and found two problems:

Commit abb0cd93494 (accel/tcg: Split out log_cpu_exec) seems to have 
broken -singlestep -d in_asm,cpu output with sh after a delay slot. Since 
that commit I get:

pc=0xac80003e sr=0x500000f1 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x00000000 fpul=0x00000000
r0=0x8cc9d000 r1=0xacc9d000 r2=0xe0000000 r3=0x8c800000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
----------------
IN:
0xac800040:  bt.s       0xac80001a

pc=0xac800040 sr=0x500000f1 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x00000000 fpul=0x00000000
r0=0x8cc9cfe0 r1=0xacc9d000 r2=0xe0000000 r3=0x8c800000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
----------------
IN:
0xac800042:  add        #-32,r1

pc=0xac800042 sr=0x500000f1 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0xac80001a fpul=0x00000000
r0=0x8cc9cfe0 r1=0xacc9d000 r2=0xe0000000 r3=0x8c800000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
in conditional delay slot (delayed_pc=0xac80001a)
pc=0xac80001a sr=0x500000f1 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0xac80001a fpul=0x00000000
r0=0x8cc9cfe0 r1=0xacc9cfe0 r2=0xe0000000 r3=0x8c800000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
pc=0xac80001c sr=0x500000f1 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0xac80001a fpul=0x00000000
r0=0x8cc9cfe0 r1=0xacc9cfe0 r2=0xe0000000 r3=0x8c800000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000

After the first delay slot no more in_asm output is printed. Going back to 
the commit before I get normal output. Then running zImage with your 
config I see:

----------------
IN:
0x8c801574:  bra        0x8c801528

pc=0x8c801574 sr=0x500000f0 pr=0x8c8013d6 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x8c801594 fpul=0x00000000
r0=0x00000007 r1=0x0000000e r2=0x8cca1084 r3=0xfffffff9
r4=0x00000137 r5=0xfffffffa r6=0x8cca1570 r7=0x00000012
r8=0x8cca1044 r9=0x00000011 r10=0x00000005 r11=0x00097d36
r12=0x8cca1014 r13=0x0000000f r14=0x8cc0183c r15=0x8cca0f80
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
----------------
IN:
0x8c801576:  add        #-7,r5

pc=0x8c801576 sr=0x500000f0 pr=0x8c8013d6 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x8c801528 fpul=0x00000000
r0=0x00000007 r1=0x0000000e r2=0x8cca1084 r3=0xfffffff9
r4=0x00000137 r5=0xfffffffa r6=0x8cca1570 r7=0x00000012
r8=0x8cca1044 r9=0x00000011 r10=0x00000005 r11=0x00097d36
r12=0x8cca1014 r13=0x0000000f r14=0x8cc0183c r15=0x8cca0f80
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
in delay slot (delayed_pc=0x8c801528)
----------------
IN:
0x8c800964:  .word 0x0000

pc=0x8c800964 sr=0x500000f1 pr=0x8c801654 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x8c800964 fpul=0x00000000
r0=0x0000001b r1=0xac8009ca r2=0x8cc9956d r3=0xfffffefe
r4=0x8cca1014 r5=0x00000000 r6=0x0142850a r7=0x8cc5001e
r8=0x8cca1044 r9=0x00000102 r10=0x00000000 r11=0x00000000
r12=0xac8009ca r13=0xac8009aa r14=0x00000000 r15=0x8cca0f28
r16=0x00000000 r17=0x500000f0 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000
----------------
IN:
0xac800000:  mov.l      0xac80007c,r1   ! 0x500000f0

pc=0xac800000 sr=0x700000f0 pr=0x00000000 fpscr=0x00040001
spc=0x00000000 ssr=0x00000000 gbr=0x00000000 vbr=0x00000000
sgr=0x00000000 dbr=0x00000000 delayed_pc=0x00000000 fpul=0x00000000
r0=0x00000000 r1=0x00000000 r2=0x00000000 r3=0x00000000
r4=0x00000000 r5=0x00000000 r6=0x00000000 r7=0x00000000
r8=0x00000000 r9=0x00000000 r10=0x00000000 r11=0x00000000
r12=0x00000000 r13=0x00000000 r14=0x00000000 r15=0x00000000
r16=0x00000000 r17=0x00000000 r18=0x00000000 r19=0x00000000
r20=0x00000000 r21=0x00000000 r22=0x00000000 r23=0x00000000

This seems to take a wrong turn at the delayed branch and somehow ends up 
at 0x8c800964 instead of 0x8c801528 but I'm not sure where to look firther 
why. I'm cc-ing Richard for both the -d cpu and this hoping he has some 
more insight.

Regards,
BALATON Zoltan