Re: [Qemu-devel] 0.9.0 and svn don't build with -march=pentium2 etc.; was: Latest SVN fails to build on Fedora Core 6 (same with 0.9.0)

From: Sunil Amitkumar Janki <psychicistnonconformist@gmail.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] 0.9.0 and svn don't build with -march=pentium2	etc.; was: Latest SVN fails to build on Fedora Core 6 (same with 0.9.0)
Date: Thu, 22 Mar 2007 21:13:00 +0100	[thread overview]
Message-ID: <4602E34C.3000106@gmail.com> (raw)
In-Reply-To: <20070322204629.5552c047@neuling>

Thomas Orgis wrote:
> Am Sun, 18 Mar 2007 09:18:40 +0000
> schrieb Nigel Horne <njh@bandsman.co.uk>: 
>
>   
>> The first part is true, the second is not, in that I already upgraded
>> to the 686 kernel, so the qemu build on FC6 is not fixed by installing the 686 kernel.
>>     
>
> So, do we have any other clue about this?
> Some qemu coder knows anything about this error?
>
>   
>> /opt/gcc34/bin/gcc -march=pentium2 -Wall -O2 -g -fno-strict-aliasing
>> -fomit-frame-pointer -I. -I.. -I/usr/src/qemu-0.9.0/target-i386
>> -I/usr/src/qemu-0.9.0 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64
>> -D_LARGEFILE_SOURCE -I/usr/src/qemu-0.9.0/fpu -DHAS_AUDIO
>> -I/usr/src/qemu-0.9.0/slirp  -c -o
>> helper.o /usr/src/qemu-0.9.0/target-i386/helper.c ../softmmu_template.h:
>> In function `__stq_mmu': ../softmmu_template.h:260: error: unable to
>> find a register to spill in class
>> `GENERAL_REGS' ../softmmu_template.h:260: error: this is the insn:
>> (insn:HI 365 364 366 13 ../softmmu_template.h:290 (parallel [ (set
>> (reg:DI 0 ax [216]) (lshiftrt:DI (reg/v:DI 59 [ val ]) (subreg:QI
>> (reg:SI 0 ax [215]) 0))) (clobber (scratch:SI)) (clobber (reg:CC 17
>> flags)) ]) 309 {lshrdi3_1} (insn_list 364 (nil)) (expr_list:REG_DEAD
>> (reg:SI 0 ax [215]) (expr_list:REG_UNUSED (reg:CC 17 flags)
>> (expr_list:REG_UNUSED (scratch:SI) (nil)))))
>> ../softmmu_template.h:260: confused by earlier errors, bailing out
>>     
>
> It is really persistent with any pentium/athlon march setting above
> pentium-mmx and alone with the -msse flag.
> If the answer is "Do Not Use GCC Arch Setting" then it would be nice to
> have it spelled out by someone else than me... of course I'd prefer
> this thing to work;-)
>
>
> Thomas.
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>
>   
I have seen this error as well when building with i686/pentium3/athlon
optimisations. As I am doing a course on x86 assembly programming
at the moment I can tell you that it suffers from register starvation
and the message tells you that there aren't enough registers left.

That's why I build QEMU on x86 with "-O2 -march=i486 -mtune=i686".

I am not a QEMU developer (yet!) but I am using it at the moment to
emulate SPARC, ARM and MIPS(EL) to build Linux executables natively
in (Slackware) Linux distributions for those architectures.

I hope to start contributing to PPC and Alpha emulation when I understand
more about QEMU's internal architecture.