On Tue, Mar 28, 2006 at 12:56:13AM +0200, Dieter Schuster wrote:
> Hello,
>
> the version 0.8.0 of qemu in the Debian-pool will not compile on
> PowerPC with GCC 3.4. The following patch will fix it:
And suck performance wise with exploding code size. Without
speaking of potential atomicity issues (although all architectures
using the byte per byte generic code may hit the problem).
>
> --- cpu-all.h~ 2005-12-19 23:51:53.000000000 +0100
> +++ cpu-all.h 2006-03-27 22:47:54.291613000 +0200
> @@ -249,15 +249,11 @@
>
> static inline void stl_le_p(void *ptr, int v)
> {
> -#ifdef __powerpc__
> - __asm__ __volatile__ ("stwbrx %1,0,%2" : "=m" (*(uint32_t *)ptr) : "r"
> (v), "r" (ptr));
> -#else
> uint8_t *p = ptr;
> p[0] = v;
> p[1] = v >> 8;
> p[2] = v >> 16;
> p[3] = v >> 24;
> -#endif
> }
>
> static inline void stq_le_p(void *ptr, uint64_t v)
>
>
> If I use GCC 3.3, then qemu compiles with the assembler instruction in
> the patch above, but qemu does not work correctly (tested with Knoppix V5.0).
Interesting, could it be an aliasing problem?
Try to compile with -fno-strict-aliasing, although
I doubt it will change anything.
>
> If I try to compile qemu with GCC 3.4 without the patch I get the following
> error:
>
> qemu-0.8.0/linux-user/elfload.c: In function `load_elf_binary':
> qemu-0.8.0/cpu-all.h:253: error: inconsistent operand constraints in an `asm'
> qemu-0.8.0/cpu-all.h:253: error: inconsistent operand constraints in an `asm'
Weird. CC'ed to gcc list despite the fact that the 3.4 branch
is definitely closed. I've not found anything remotely similar
from bugzilla.
>
> But if I copy the function stl_le_p to a seperate file, the function
> will compile with GCC 3.4.
Which gcc-3.4 (gcc -v)?
>
> Is this a bug in qemu, or is it a bug in GCC 3.4?
It looks like a compiler bug. But you should
provide an environment independent test case,
i.e., the preprocessed source. Please try
also to provide a minimal failing test case
(it may be hard given the symptoms).
Regards,
Gabriel
