x86, fpu: decouple non-lazy/eager fpu restore from xsave

Decouple non-lazy/eager fpu restore policy from the existence of the xsave
feature. Introduce a synthetic CPUID flag to represent the eagerfpu
policy. "eagerfpu=on" boot paramter will enable the policy.

Requested-by: H. Peter Anvin <hpa@zytor.com>
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-2-git-send-email-suresh.b.siddha@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ad7e2e5088c1..741d064fdc6a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1833,6 +1833,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         and restore using xsave. The kernel will fallback to
                         enabling legacy floating-point and sse state.
 
+        eagerfpu=       [X86]
+                        on      enable eager fpu restore
+                        off     disable eager fpu restore
+
         nohlt           [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
                         wfi(ARM) instruction doesn't work correctly and not to
                         use it. This is also useful when using JTAG debugger.