[coyotos-dev] I love Intel

[William Leslie]

On Dec 30, 2007 4:01 PM, Jonathan S. Shapiro <shap at eros-os.com> wrote:

> William:
>
> Kernel virtual address space is very tight and therefore very precious.
> Devoting a 4M region to solving the F00F bug problem is therefore not
> workable. We simply don't have 4M of virtual region to spare.


>
> Also, you truly don't want to cause a page fault on these references, so
> the right "fix" is to make the page uncacheable. This tends to have the
> effect that the IDT page cannot be shared with anything else.


If the page is read only, all this means is that code that changes the IDT
needs to fiddle with the permissions before and after the change. It might
be a hack, but at least it is reasonably well contained- it doesn't require
architectural changes.

Unless I'm missing something. How often will a read-only IDT fault under
normal usage?

William
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