Merge branch 'x86-bsp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kernel / head_32.S

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index a013e7390ab571e2832b90bdf53d493499e5440b..8e7f6556028f7ff50d90c73eac405d3cdcb7b881 100644 (file)
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -305,8 +305,8 @@ 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
@@ -321,6 +321,11 @@ 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