[Bug libc/12420] New: On AMD64 linux, getcontext resets FPU exception mask.

["jean.claude.beaudoin at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=12420

           Summary: On AMD64 linux, getcontext resets FPU exception mask.
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper.fsp@gmail.com
        ReportedBy: jean.claude.beaudoin@gmail.com


Created attachment 5202
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5202
small demo to be linked with -lm

The attached program demonstrates that the floating-point exception
mask is being reset to 0 (effectively cleared) by getcontext().

The problem does not exist on i386 since the implementation of
getcontext() on it properly executes a fldenv right after the
fnstenv (as justified by the very informative comment to be seen
in the source code getcontext.S).

Seen on Ubuntu 10.10, Fedora 12 and Fedora 14 at least.
>From reading the current source code, current git code should have
the same problem.

Cheers,

Jean-Claude Beaudoin

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