Messages in this thread | | | Date | Sat, 18 Nov 2000 09:15:36 -0500 | From | Brian Gerst <> | Subject | Re: Freeze on FPU exception with Athlon |
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Linus Torvalds wrote: > > In article <20001118014019.18006.qmail@web3404.mail.yahoo.com>, > =?iso-8859-1?q?Markus=20Schoder?= <markus_schoder@yahoo.de> wrote: > >The following small program (linked against glibc 2.1.3) reliably > >freezes my system (Athlon Thunderbird CPU) with at least kernels > >2.4.0-test10 and 2.4.0-test11-pre5. Even the SysRq keys do not work > >after the freeze. > > > >Older kernels (e.g. 2.3.40) seem to work. Any Ideas? > > It certainly doesn't happen for me on any of the machines I work with, > but it wouldn't compile as-is for me, so I exchanged the FPU setting > with a simpler > > asm("fldcw %0": :"m" (0)); > > which should do the equivalent (ie unmask divide by zero errors). Does > that make a difference for you? > > Can you try to figure out where it started happening? Ie try test9 and > back too, to figure out what might be bringing it on... > > I sure as hell hope this isn't an Athlon issue. Can other people try > the test-program and see if we have a pattern (ie "it happens only on > Athlons", or "Linus is on drugs and it happens for everybody else"). > > Thanks, > > Linus
I get Floating Point Exception (core dumped), but I needed to use the modified program below to keep GCC from optimizing the division away as a constant. This is on test11-pre5.
-------------- #define _GNU_SOURCE
#include <fenv.h> #include <unistd.h>
double a =1.0, b = 0.0; int main(void) { double c; asm("fldcw %0": :"m" (0)); // fesetenv(FE_NOMASK_ENV); c = a / b; sleep(10); return a; } -------------- processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 2 model name : AMD Athlon(tm) Processor stepping : 2 cpu MHz : 748.000573 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes features : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow bogomips : 1494.22
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