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SubjectRe: [patch] SMP alternatives
Alan Cox wrote:
> On Mer, 2005-11-23 at 12:17 -0700, Andi Kleen wrote:
>>> + /* Paranoia */
>>> + asm volatile ("jmp 1f\n1:");
>>> + mb();
>> That would be totally obsolete 386 era paranoia. If anything then use
>> a CLFLUSH (but not available on all x86s)
>
> If you are patching code another x86 CPU is running you must halt the
> other processors and ensure it executes a serialzing instruction before
> it enters any patched code.

Patching in/out SMP-locking with more than one active CPU would be a
pretty silly idea in the first place ;)

> How many kilobytes of tables do you add to the kernel to do this
> pointless stunt btw ?

16 .smp_altinstructions 0000ae0b c03b4000 003b4000 002b4000 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
17 .smp_altinstr_replacement 00000f6e c03bee0b 003bee0b 002bee0b 2**0
CONTENTS, ALLOC, LOAD, CODE
cheers,

Gerd

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