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SubjectRe: TSCs are a no-no on i386
Alan Cox wrote:
> On Mer, 2003-07-30 at 22:50, Petr Vandrovec wrote:
> > There is no such instruction. Skip LOCK prefix and decode again,
> > you'll get either cmpxchg or xadd (or cmpxchg8b, but then it does
> > not work on i486 too).
>
> And if the byte you are looking at was patched by another thread you've
> blown it. Your emulation can only be so good 8) People do stuff like
> patching instructions under software decode as a robustness check - its
> normally pretty amusing

On a uniprocessor 386, this is not a problem. Just disable preemption
in the kernel decoder.

Of course if you do it in userspace using SIGILL, then it is broken :)

-- Jamie

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