Re: [Qemu-devel] /* XXX: suppress this hack */

[Magnus Damm]

Hello there, thanks for the reply!

[snip]

> > I would like to "suppress that hack", ie make sure that AREG4 to AREG11
> > gets defined for i386-softmmu. Someone that knows the code - what needs
> > to be done? Just removing the ifdef does not work for sure. Is it some
> > issue with setjmp()/longjmp()? I'm willing to set aside some hours to
> > fix this if someone who knows points me in the right direction.
> 
> It's all about ABIs: see
> 
> http://www-106.ibm.com/developerworks/linux/library/l-ppc/#h4
> 
> You want all those registers you use to be volatile, i.e. every function
> which wants to use one of those has to make sure that their original
> contents gets restored before returning.

Yeah, registers "r3" to "r12" are "caller save", ie these registers must
be saved before a function is called. But what about "r16" to "r23",
these are currently only used when CONFIG_USER_ONLY is set - I thought
that they were supposed to be saved by the called function prior use,
"callee save". But how does that affect the softmmu code in a bad way
but the user code works? Any ideas?

Thanks!

/ magnus