[OpenBIOS] SOLVED: the mystery of Solaris on SPARC32 and the missing Forth arguments

[Blue Swirl]

On Mon, Oct 18, 2010 at 7:43 PM, Mark Cave-Ayland
<mark.cave-ayland at siriusit.co.uk> wrote:
> Artyom Tarasenko wrote:
>
>>> Does this sound reasonable? I'm surprised that one else has realised that
>>> the obp_fortheval_v2 function signature was wrong, but I guess it
>>> probably
>>> hardly gets used for anything these days.
>>
>> Ops. Forgot to submit this patch back then. :(. Sorry.
>> The reason was not getting too far with the patch, because of the
>> broken memory management.
>
> Okay; I've committed something which should do the trick to SVN as r915.
>
> Hmmmm these symptoms look exactly like something on SPARC64 where various
> bits of memory were getting clobbered because of a lack of stack space...
> (goes and has a look)...
>
> Right - it's definitely something related to the stack when calling from the
> client into OpenBIOS (or vice-versa). If you take a look at
> arch/sparc32/context.c and start increasing IMAGE_STACK_SIZE, say to 16K or
> 32K you'll see that things suddenly start to work much better.
>
> I think its related to the flushing of register windows onto the stack when
> switching between the two. My thoughts are that this is probably related to
> Igor's SPARC64 patches here:
>
> http://www.openfirmware.info/pipermail/openbios/2009-July/003762.html
>
> I suspect that you'll need to come up with something along similar lines for
> SPARC32. Blue, any thoughts?

On Sparc32 the client interface is not used and there is no 'flushw'
instruction, but otherwise saving and restoring %g registers and
flushing windows may be helpful.