[PATCH] i386: Verify important CPUID bits in real mode

Check some CPUID bits that are needed for compiler generated early in boot.
When the system is still in real mode before changing the VESA BIOS mode
it is possible to still display an visible error message on the screen.

Similar to x86-64.

Includes cleanups from Eric Biederman

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 34 insertions, 0 deletions

diff --git a/include/asm-i386/required-features.h b/include/asm-i386/required-features.h
new file mode 100644
index 000000000000..9db866c1e64c
--- /dev/null
+++ b/include/asm-i386/required-features.h
@@ -0,0 +1,34 @@
+#ifndef _ASM_REQUIRED_FEATURES_H
+#define _ASM_REQUIRED_FEATURES_H 1
+
+/* Define minimum CPUID feature set for kernel These bits are checked
+   really early to actually display a visible error message before the
+   kernel dies.  Only add word 0 bits here
+
+   Some requirements that are not in CPUID yet are also in the
+   CONFIG_X86_MINIMUM_CPU mode which is checked too.
+
+   The real information is in arch/i386/Kconfig.cpu, this just converts
+   the CONFIGs into a bitmask */
+
+#ifdef CONFIG_X86_PAE
+#define NEED_PAE        (1<<X86_FEATURE_PAE)
+#else
+#define NEED_PAE        0
+#endif
+
+#ifdef CONFIG_X86_CMOV
+#define NEED_CMOV       (1<<X86_FEATURE_CMOV)
+#else
+#define NEED_CMOV       0
+#endif
+
+#ifdef CONFIG_X86_CMPXCHG64
+#define NEED_CMPXCHG64  (1<<X86_FEATURE_CX8)
+#else
+#define NEED_CMPXCHG64  0
+#endif
+
+#define REQUIRED_MASK1  (NEED_PAE|NEED_CMOV|NEED_CMPXCHG64)
+
+#endif