Description of problem:

I don't have a small test case yet (I'll attach it when I do), but something
in the vicinity of the SSE registers and debugging operations is screwed
up. I have a debugger regression test that fails in x86_64 fedora 11 and
passes on the exact same machine running the exact same debugger in
x86_64 fedora 10.

The symptom is that a xmm register I modify with ptrace pokeuser
does not show up with the same value in the process when I run it later,
but the details are complex, and I haven't made a simple case fail yet.

I just thought I'd go ahead and create this bugzilla in case someone else
runs across the problem or knows it is already fixed in an upcoming kernel.

Version-Release number of selected component (if applicable):
kernel-2.6.29.5-191.fc11.x86_64

How reproducible:
every time in my complicated testbed

Steps to Reproduce:
1.run testbed
2.see failure (no much help, I know).
3.
  
Actual results:
Just to give an example, the debugged process that has been modified
winds up printing:
patched output = 5.4902e-315

Expected results:
When if the register modification had worked, it would have printed:
patched output = 47

Additional info:
On fedora 10, the kernel that worked was:
kernel-2.6.27.25-170.2.72.fc10.x86_64

There are also many other linux distributions which run the test with
no failures.