diff options
| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-12-18 10:22:27 +1100 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-12-18 10:22:27 +1100 |
| commit | 376bddd34433065aeb9b9a140870537feecf90ef (patch) | |
| tree | a40e2b84ad89f4b3ba968de65a4bf7ff6ccae835 /arch/x86/kernel/head_32.S | |
| parent | d526e85f60fce9aa2a1432cbd06e3cf20c1644c8 (diff) | |
| parent | 667b504a2c411e4d5915a6e2260a3857ba9f797a (diff) | |
Merge remote-tracking branch 'agust/next' into next
Brings some 52xx updates. Also manually merged tools/perf/perf.h.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/x86/kernel/head_32.S')
| -rw-r--r-- | arch/x86/kernel/head_32.S | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 957a47aec64..4dac2f68ed4 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -292,8 +292,8 @@ default_entry: * be using the global pages. * * NOTE! If we are on a 486 we may have no cr4 at all! - * Specifically, cr4 exists if and only if CPUID exists, - * which in turn exists if and only if EFLAGS.ID exists. + * Specifically, cr4 exists if and only if CPUID exists + * and has flags other than the FPU flag set. */ movl $X86_EFLAGS_ID,%ecx pushl %ecx @@ -308,6 +308,11 @@ default_entry: testl %ecx,%eax jz 6f # No ID flag = no CPUID = no CR4 + movl $1,%eax + cpuid + andl $~1,%edx # Ignore CPUID.FPU + jz 6f # No flags or only CPUID.FPU = no CR4 + movl pa(mmu_cr4_features),%eax movl %eax,%cr4 |