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SubjectRe: TSCs are a no-no on i386
Alan Cox wrote:
> > > 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.
> Wrong again. Thats a common myth but you see I can put the instruction on a page
> so that its executed from a page I just did a read() into in another process. If
> I'm really bored I'll use O_DIRECT but thats mostly for makign life really bad
> for non cache coherent setups 8)

I wouldn't be surprised if even real CPUs mis-decode when there's a
concurrent DMA into the area they are reading instructions from! :)

-- Jamie
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