Приколы Via C3
Dave Jones wrote:
> On Wed, Jan 15, 2003 at 10:29:01AM +0100, Miklos Szeredi wrote:
> >
> > I just bought a VIA C3 866 processor, and under very special
> > circumstances some programs (e.g. mplayer, xmms) randomly crash with
> > trace/breakpoint trap or segmentation fault. Otherwise the system
> > seems stable even under high load.
>
> Be sure that those programs aren't compiled for 686. The C3 lacks
> cmov, so it'll segfault when it hits that opcode. You can confirm
> this by running it under gdb, and disassembling where it segv's to.
> This is still a common problem thats biting some people. The debian
> folks had a broken libssl for months up until recently.
>
> Note to userspace developers: If you're compiling something as
> a 686 binary, you *NEED* to check the feature flags (in an i386
> compiled program) to see if the CPU has cmov before you load 686
> optimised parts of your app. This is *NOT* a kernel problem,
> it is *NOT* a CPU bug. The cmov extension is optional.
> VIA chose to save silicon space by not implementing it.
> Gcc unfortunatly always uses cmov when compiling for 686.
> On Wed, Jan 15, 2003 at 10:29:01AM +0100, Miklos Szeredi wrote:
> >
> > I just bought a VIA C3 866 processor, and under very special
> > circumstances some programs (e.g. mplayer, xmms) randomly crash with
> > trace/breakpoint trap or segmentation fault. Otherwise the system
> > seems stable even under high load.
>
> Be sure that those programs aren't compiled for 686. The C3 lacks
> cmov, so it'll segfault when it hits that opcode. You can confirm
> this by running it under gdb, and disassembling where it segv's to.
> This is still a common problem thats biting some people. The debian
> folks had a broken libssl for months up until recently.
>
> Note to userspace developers: If you're compiling something as
> a 686 binary, you *NEED* to check the feature flags (in an i386
> compiled program) to see if the CPU has cmov before you load 686
> optimised parts of your app. This is *NOT* a kernel problem,
> it is *NOT* a CPU bug. The cmov extension is optional.
> VIA chose to save silicon space by not implementing it.
> Gcc unfortunatly always uses cmov when compiling for 686.
Интересно, он тебя понял или просто боится спросить?
Ну я прочитал из-за чего такой прикол произошёл, но ессно не врубился. А что?
проц не поддерживает одну из опциональных иструкций, в то время как компиляторы её активно юзают
это в общих чертах
это в общих чертах
Ещё проще: VIA сосёт. Или: GCC - говно.
Обобщая: Intel рулит.
Обобщая: Intel рулит.
Насколько я помню, они там один из блоков в ядре не сделали, сэкономили типа+меньше проц греется, только считает плохо. Странно что он вообще мпег 4-й гонял, немерянно долго правда, но всё же перегнал.
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Amitola
Недавно ворошил старые статьи на ixbt и повстречал такой скриншот: