[Xen-devel] [tip:x86/urgent] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing"

[tip-bot for Andy Lutomirski <tipbot@xxxxxxxxx>]

Commit-ID:  426d1aff3138cf38da14e912df3c75e312f96e9e
Gitweb:     http://git.kernel.org/tip/426d1aff3138cf38da14e912df3c75e312f96e9e
Author:     Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Fri, 9 Dec 2016 10:24:06 -0800
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 19 Dec 2016 11:54:20 +0100

Revert "x86/boot: Fail the boot if !M486 and CPUID is missing"

This reverts commit ed68d7e9b9cfb64f3045ffbcb108df03c09a0f98.

The patch wasn't quite correct -- there are non-Intel (and hence
non-486) CPUs that we support that don't have CPUID.  Since we no
longer require CPUID for sync_core(), just revert the patch.

I think the relevant CPUs are Geode and Elan, but I'm not sure.

In principle, we should try to do better at identifying CPUID-less
CPUs in early boot, but that's more complicated.

Reported-by: One Thousand Gnomes <gnomes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Matthew Whitehead <tedheadster@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: xen-devel <Xen-devel@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: 
http://lkml.kernel.org/r/82acde18a108b8e353180dd6febcc2876df33f24.1481307769.git.luto@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
 arch/x86/boot/cpu.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/boot/cpu.c b/arch/x86/boot/cpu.c
index 4224ede..26240dd 100644
--- a/arch/x86/boot/cpu.c
+++ b/arch/x86/boot/cpu.c
@@ -87,12 +87,6 @@ int validate_cpu(void)
                return -1;
        }
 
-       if (CONFIG_X86_MINIMUM_CPU_FAMILY <= 4 && !IS_ENABLED(CONFIG_M486) &&
-           !has_eflag(X86_EFLAGS_ID)) {
-               printf("This kernel requires a CPU with the CPUID instruction.  
Build with CONFIG_M486=y to run on this CPU.\n");
-               return -1;
-       }
-
        if (err_flags) {
                puts("This kernel requires the following features "
                     "not present on the CPU:\n");

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