Re: [Qemu-devel] Re: [RFC] OSX/ppc64 TCG support

[Andreas Färber]

Am 11.04.2009 um 09:22 schrieb malc:

> On Sat, 11 Apr 2009, Andreas F?rber wrote:
> > ii) In ppc64/tcg-target.c tcg_target_call_oarg_regs is declared  
> > with a
> > length of 2 but only contains one register. Intended?
>
> Probably not, then again i'd have to recheck PPC64 ABI for DI/struct
> returns to be sure, then again QEMU doesn't sue those. Anyhow...
>
> > diff --git a/tcg/ppc64/tcg-target.c b/tcg/ppc64/tcg-target.c
> > index a96314c..2a8eaec 100644
> > --- a/tcg/ppc64/tcg-target.c
> > +++ b/tcg/ppc64/tcg-target.c
> > @@ -125,11 +134,15 @@ static const int tcg_target_call_iarg_regs[]  
> > = {
> >    TCG_REG_R10
> > };
> >
> > -static const int tcg_target_call_oarg_regs[2] = {
> > +static const int tcg_target_call_oarg_regs[1] = {
> >    TCG_REG_R3
> > };
>
> This is most certainly is just as in correct as having it at [2] and
> not initializing element N1 since main tcg proper never invokes  
> ARRAY_SIZE
> on tcg_target_call_oarg_regs...

Oops, I must have confused this with iargs, there the ARRAY_SIZE is  
checked in tcg_target_get_call_iarg_regs_count.
Anyway, I had already tried adding TCG_REG_R4 like for ppc, without  
noticeable difference.

> > Unfortunately qemu-system-ppc still crashes immediately, any hints  
> > welcome.
> >
> > Program received signal EXC_BAD_INSTRUCTION, Illegal instruction/ 
> > operand.
> > 0x00000000005a9680 in code_gen_prologue ()
> > (gdb) bt
>
> I think TOCs are a lot different in ppc-elf64abi and Mach-O one, that
> would explain why it fails so early

Could you please elaborate on that? I am still not familiar with the  
topic. Do you mean I would have to initialize the TOC field of the  
function descriptor? Or in which other parts of the code would I need  
to make adjustments for those TOCs?
In the above ABI document neither function descriptors nor TOCs are  
mentioned at all.

> > #0  0x00000000005a9680 in code_gen_prologue ()
>
> [..snip..]
>
> Unfortunatelly i don't have access to MacOSX on a PPC64 so you are  
> on your
> own there.

I know, you said so. Still any hints where to dig or advice how to  
debug this with gdb would be helpful.

Andreas