Re: [9fans] unable to start plan9 on atom330 in virtualbox

[Josh Marshall <joshua.r.marshall.1991@gmail.com>]

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Is there a resource whereby I could pickup this kind of debug skill, or is
this experience, and assembly knowledge?

On Mon, Jun 13, 2011 at 3:01 AM, <cinap_lenrek@gmx.de> wrote:

> ok, i think i can explain the "unlock of ilock: pc f0140fc5, held by ..."
> message.
>
> i extracted that 9pcflop kernel with muzgos cdfpart from the current iso
> and
> disassembled with acid arround.
>
> the routine that calls unlock looks like this:
>
> the routine that calls the unlock (shutdown from ether79c970.c)
> 0xf0140f79 0xf0140f79   SUBL    $0x14,SP
> 0xf0140f7c 0xf0140f7c   MOVL    0x18(SP),AX
> # ctlr = arg->foobar
> 0xf0140f80 0xf0140f80   MOVL    0x78(AX),CX
> 0xf0140f83 0xf0140f83   MOVL    CX,0x10(SP)
> 0xf0140f87 0xf0140f87   MOVL    CX,0x0(SP)
> # ilock(ctlr)
> 0xf0140f8a 0xf0140f8a   CALL    0xf019af31
> 0xf0140f8f 0xf0140f8f   MOVL    0x10(SP),AX
> 0xf0140f93 0xf0140f93   MOVL    AX,0x0(SP)
> 0xf0140f96 0xf0140f96   MOVL    $0x18,AX
> 0xf0140f9b 0xf0140f9b   MOVL    AX,0x4(SP)
> # io32r(ctlr, 0x18) ???
> 0xf0140f9f 0xf0140f9f   CALL    0xf01409b4
> 0xf0140fa4 0xf0140fa4   MOVL    0x10(SP),AX
> 0xf0140fa8 0xf0140fa8   MOVL    AX,0x0(SP)
> 0xf0140fab 0xf0140fab   MOVL    $0x18,AX
> 0xf0140fb0 0xf0140fb0   MOVL    AX,0x4(SP)
> # io16r(ctlr, 0x18);
> 0xf0140fb4 0xf0140fb4   CALL    0xf014093f
> 0xf0140fb9 0xf0140fb9   MOVL    0x10(SP),AX
> 0xf0140fbd 0xf0140fbd   MOVL    AX,0x0(SP)
> # unlock(ctlr)
> 0xf0140fc0 0xf0140fc0   CALL    0xf019b0be
> 0xf0140fc5 0xf0140fc5   ADDL    $0x14,SP
> 0xf0140fc8 0xf0140fc8   RET
>
> it have no debug symbols so i looked for magic numbers
> arround (in this case 0x18)
>
> wich turned out to be:
>
> ether79c970.c:31:       Sreset          = 0x0018,       /* software reset
> */
>
> # this looks like io32r() from ether79c970.c
> acid: asm(0xf01409b4)
> 0xf01409b4 0xf01409b4   SUBL    $0x8,SP
> 0xf01409b7 0xf01409b7   MOVL    0xc(SP),CX
> # port = arg2
> 0xf01409bb 0xf01409bb   MOVL    0x1c(CX),CX
> # port += arg1
> 0xf01409be 0xf01409be   ADDL    0x10(SP),CX
> 0xf01409c2 0xf01409c2   MOVL    CX,0x0(SP)
> # inl(port)
> 0xf01409c5 0xf01409c5   CALL    0xf010036e
> 0xf01409ca 0xf01409ca   ADDL    $0x8,SP
> 0xf01409cd 0xf01409cd   RET
>
> # this is inl()
> acid: asm(0xf010036e)
> 0xf010036e 0xf010036e   MOVL    0x4(SP),DX
> 0xf0100372 0xf0100372   INL     DX,AX
> 0xf0100373 0xf0100373   RET
>
> so there is your bug!
>
> static void
> shutdown(Ether *ether)
> {
>        Ctlr *ctlr;
>
>        ctlr = ether->ctlr;
>        ilock(ctlr);
>        io32r(ctlr, Sreset);
>        io16r(ctlr, Sreset);
>        unlock(ctlr);
> }
>
> it was commented out before...
>
> the file just changed... i think they try to fix it right now...
>
> --
> cinap
>
>

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