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SIGFPE / fputest 
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Yorick Master

Joined: Wed Jun 01, 2005 11:34 am
Posts: 112
Post SIGFPE / fputest
When running "make reloc" on the current Yorick (cloned from github), a working Yorick results. However, I notice this in the output on the screen:

Code:
  ============= begin play/unix configuration =============

using getrusage() (CPU timer)
using gettimeofday() (wall timer)
using POSIX getlogin(), getpwuid(), getuid() functions
using POSIX tcgetpgrp() function
using POSIX getcwd() function
using POSIX dirent.h header for directory ops
using poll(), poll.h header
using FPU_GCC_X86_64 (SIGFPE delivery)
./config.sh: line 328: 11425 Floating point exception./fputest

*************************WARNING***************************
*** play/unix configuration failed to get SIGFPE delivered
*** read the notes in play/unix/README.fpu
*************************WARNING***************************

configured plugins for Linux
wrote config.h, ../../Make.cfg

  ============== end play/unix configuration ==============


Looking around on the forums I found a thread that discusses SIGFPE/fputest: viewtopic.php?f=7&t=345&p=1139#p1139

It sounds like in that thread, the test was actually preventing Yorick from building properly. So I am not having that problem. And in fact, if I start up Yorick I can do the following:

Code:
> 1/0.
ERROR (*main*) Floating point interrupt (SIGFPE)
WARNING source code unavailable (try dbdis function)
now at pc= 1 (of 11), failed at pc= 5
To enter debug mode, type <RETURN> now (then debexit to get out)
>


So it appears to me that Yorick is properly catching SIGFPE.

In the post I cited, it says:

munro wrote:
For reasons I do not understand, the SIGFPE delivery works in yorick, even though it fails in fputest.c.


This sounds to me like the error encountered during the install is actually a known issue and that it doesn't necessarily mean there's a problem? I didn't see anything further about this in README.fpu. Does this mean I can just ignore the warning?

I'm running on a 64-bit linux installation; I believe it's RHEL 5. In case it's helpful, here's what /proc/cpuinfo has to say (it actually outputs 8 total processor entries since we have 2 quad-core processors but they are all identical):

Code:
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Xeon(R) CPU           E5430  @ 2.66GHz
stepping        : 6
cpu MHz         : 2659.999
cache size      : 6144 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
apicid          : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr sse4_1 lahf_lm
cache_alignment : 64
address sizes   : 38 bits physical, 48 bits virtual
power management:


Fri Feb 01, 2013 8:40 am
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Yorick Master

Joined: Mon Nov 22, 2004 9:43 am
Posts: 354
Location: Livermore, CA, USA
Post Re: SIGFPE / fputest
Ignore it. It is a bug in all recent linux kernels. My worry is that someday whatever goes wrong in fputest will go wrong in yorick itself. The fputest program is simple enough that someone skilled at kernel debugging could use it to figure out what's wrong. I had a look at doing that several years ago and couldn't do it myself. Judging from the kernel forums, unless you have an actual patch to suggest, they are even less likely to pay any attention to you.


Wed Feb 06, 2013 9:59 am
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Yorick Master

Joined: Wed Jun 01, 2005 11:34 am
Posts: 112
Post Re: SIGFPE / fputest
Okay, will ignore. Thanks! :)


Thu Feb 07, 2013 4:06 pm
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