diff options
| author | Ingo van Lil <[email protected]> | 2011-09-14 16:21:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2011-09-14 18:09:37 -0700 |
| commit | fbfe9c847edf57ac8232aeafb290f272289893a3 (patch) | |
| tree | da25f3f4ece74b9fa328ce3884f19ff18eff516d /lib/mpi/mpiutil.c | |
| parent | b40997b872cdb70140f127af6069f00a86b6cf81 (diff) | |
um: Save FPU registers between task switches
Some time ago Jeff prepared 42daba316557 ("uml: stop saving process FP
state") for UML to stop saving the process FP state between task
switches. The assumption was that since with SKAS0 every guest process
runs inside a host process context the host OS will take care of keeping
the proper FP state.
Unfortunately this is not true for multi-threaded applications, where
all guest threads share a single host process context yet all may use
the FPU on their own. Although I haven't verified it I suspect things
to be even worse in SKAS3 mode where all guest processes run inside a
single host process.
The patch reintroduces the saving and restoring of the FP context
between task switches.
[[email protected]: Ingo posted this patch in 2009, sadly it was never applied
and got lost. Now in 2011 the problem was reported by Gunnar.]
Signed-off-by: Ingo van Lil <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>
Reported-by: <[email protected]>
Tested-by: <[email protected]>
Cc: Stanislav Meduna <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Diffstat (limited to 'lib/mpi/mpiutil.c')
0 files changed, 0 insertions, 0 deletions