mxcsr and ucontext_t on x86 GNU/Linux

[Drew Hess]

Hi,

How does one access the saved state of the mxcsr register in a signal
handler on x86 GNU/Linux?  The _libc_fpstate struct in
/usr/include/sys/ucontext.h doesn't include that register (not in GNU libc
2.3.2, at least), even though the kernel's own _fpstate struct does on
recent kernels.

If no other alternative exists, is it safe to #include <asm/sigcontext.h>
and typecast the libc fpregset_t to an _fpstate so that I can access the
mxcsr?  It's ugly, but the code where I need to do this stuff is already
doing some pretty platform-specific things anyway, like using the
_SET_FPUCW macros from GNU libc.


thanks
-dwh-