1 files changed, 65 insertions, 0 deletions

diff --git a/arch/i386/kernel/verify_cpu.S b/arch/i386/kernel/verify_cpu.S
new file mode 100644
index 000000000000..e51a8695d54e
--- /dev/null
+++ b/arch/i386/kernel/verify_cpu.S
@@ -0,0 +1,65 @@
+/* Check if CPU has some minimum CPUID bits
+   This runs in 16bit mode so that the caller can still use the BIOS
+   to output errors on the screen */
+#include <asm/cpufeature.h>
+
+verify_cpu:
+        pushfl                          # Save caller passed flags
+        pushl   $0                      # Kill any dangerous flags
+        popfl
+
+#if CONFIG_X86_MINIMUM_CPU_MODEL >= 4
+        pushfl
+        orl     $(1<<18),(%esp)         # try setting AC
+        popfl
+        pushfl
+        popl    %eax
+        testl   $(1<<18),%eax
+        jz      bad
+#endif
+#if REQUIRED_MASK1 != 0
+        pushfl                          # standard way to check for cpuid
+        popl    %eax
+        movl    %eax,%ebx
+        xorl    $0x200000,%eax
+        pushl   %eax
+        popfl
+        pushfl
+        popl    %eax
+        cmpl    %eax,%ebx
+        pushfl                          # standard way to check for cpuid
+        popl    %eax
+        movl    %eax,%ebx
+        xorl    $0x200000,%eax
+        pushl   %eax
+        popfl
+        pushfl
+        popl    %eax
+        cmpl    %eax,%ebx
+        jz      bad                     # REQUIRED_MASK1 != 0 requires CPUID
+
+        movl    $0x0,%eax               # See if cpuid 1 is implemented
+        cpuid
+        cmpl    $0x1,%eax
+        jb      bad                     # no cpuid 1
+
+        movl    $0x1,%eax               # Does the cpu have what it takes
+        cpuid
+
+#if CONFIG_X86_MINIMUM_CPU_MODEL > 4
+#error  add proper model checking here
+#endif
+
+        andl    $REQUIRED_MASK1,%edx
+        xorl    $REQUIRED_MASK1,%edx
+        jnz     bad
+#endif /* REQUIRED_MASK1 */
+
+        popfl
+        xor     %eax,%eax
+        ret
+
+bad:
+        popfl
+        movl    $1,%eax
+        ret