Re: [9fans] plan9 go output faults on 9vx but ok on cpu

[Pavel Zholkover <paulzhol@gmail.com>]

On Sat, Jan 15, 2011 at 4:00 AM, Anthony Martin <ality@pbrane.org> wrote:
> Pavel Zholkover <paulzhol@gmail.com> once said:
>> I have no idea what is causing it to die, I've tried adding a bunch of
>> INT $3 to see how far in the flow I can get, but all I get this:
>>
>> 9vx panic: unknown trap/intr: 0x203
>> aborting, to dump core.
>>
>> for an INT $3 just before
>> CALL  SI      // fn()
>
> This happens because the linker outputs the two bytes
> { 0xCD, 0x03 } for an INT $3 instruction but libvx32
> only sends a VXTRAP_BREAKPOINT to 9vx if it sees an
> INT3 instruction (a single 0xCC byte). Try using a
> 'BYTE $0xCC' instead.
>
>  Anthony

Thanks, that did the trick.

This is what I get when running goroutines on 9vx with a 0xCC
breakpoint compiled in:
% goroutines
goroutines 69: suicide: sys: breakpoint pc=0x00009e44
id: 1 0
id: 1 1
id: 1 2
id: 1 3
id: 1 4
id: 1 5
id: 1 6
id: 1 7
id: 1 8
id: 1 9
% acid 69
/proc/69/text:386 plan 9 executable
/sys/lib/acid/port
/sys/lib/acid/386
no symbol information
acid: regs()
PC      0x00009e44 0x9e44  ?file?:0
SP      0x000560e0 ECODE 0x00000000 EFLAG 0x00000000
CS      0x00000000 DS    0x00000000 SS  0x00000000
GS      0x00000000 FS    0x00000000 ES  0x00000000
TRAP    0x00000003 breakpoint
AX      0x0004c0c0 BX   0x0004c0c0 CX   0x0fffffc8 DX   0x00054100
DI      0x00056100 SI   0x000072f8 BP   0x00000000

acid: asm(*PC-32)
0x9e24 0x00009e24       ADDL    $0x1ed2c,AX
0x9e29 0x00009e29       MOVL    DX,0xfffffff8(AX)
0x9e2c 0x00009e2c       MOVL    BX,0xfffffffc(AX)
0x9e2f 0x00009e2f       MOVL    0x1ed2c,AX
0x9e35 0x00009e35       MOVL    0x30(AX),AX
0x9e38 0x00009e38       MOVL    AX,0x24(BX)
0x9e3b 0x00009e3b       CALL    0x1c10
0x9e40 0x00009e40       MOVL    0x0(DX),DX
0x9e42 0x00009e42       MOVL    0x0(BX),BX
0x9e44 0x00009e44       INT     3  <=== we stopped here,
runtime.rfork() in src/pkg/runtime/plan9/sys.s
0x9e45 0x00009e45       CALL*   SI
0x9e47 0x00009e47       CALL    0x9eac
0x9e4c 0x00009e4c       RET

0x72f8 is runtime.mstart as it should...

acid: asm(*SI)
0x72f8 0x000072f8       MOVL    0x1ed2c,CX
0x72fe 0x000072fe       MOVL    0xfffffff8(CX),CX
0x7301 0x00007301       CMPL    0x0(CX),SP
0x7303 0x00007303       JHI     0x730e
0x7305 0x00007305       XORL    DX,DX
0x7307 0x00007307       XORL    AX,AX
0x7309 0x00007309       CALL    0x1a75
0x730e 0x0000730e       SUBL    $0x8,SP
0x7311 0x00007311       MOVL    0x1ed2c,AX
0x7317 0x00007317       MOVL    0xfffffff8(AX),AX
0x731a 0x0000731a       MOVL    0x1ed2c,CX
0x7320 0x00007320       MOVL    0xfffffffc(CX),CX
0x7323 0x00007323       MOVL    0x0(CX),CX
0x7325 0x00007325       CMPL    CX,AX
0x7327 0x00007327       JEQ     0x7336
0x7329 0x00007329       MOVL    $0x1eb80,AX
0x732e 0x0000732e       MOVL    AX,0x0(SP)
0x7331 0x00007331       CALL    0x81ee
0x7336 0x00007336       MOVL    0x1ed2c,AX
0x733c 0x0000733c       MOVL    0xfffffffc(AX),AX
0x733f 0x0000733f       MOVL    0x94(AX),AX
0x7345 0x00007345       CMPL    AX,$0x0
0x7348 0x00007348       JNE     0x735e
0x734a 0x0000734a       CALL    0x2d75
0x734f 0x0000734f       MOVL    0x1ed2c,CX
0x7355 0x00007355       MOVL    0xfffffffc(CX),CX
0x7358 0x00007358       MOVL    AX,0x94(CX)
0x735e 0x0000735e       CALL    0x9e4d
0x7363 0x00007363       CALL    0x74c3
0x7368 0x00007368       ADDL    $0x8,SP

I can't tell from this why 9vx is dying on me and I don't know how to
use acid to debug a child process after rfork,
is there something like gdb's set follow-fork-mode child ?

Pavel