| Date | Fri, 21 Sep 2012 15:12:08 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 00/11] x86: Supervisor Mode Access Prevention |
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On 09/21/2012 03:07 PM, Eric W. Biederman wrote: > > Have you tested kexec in this environment? > > This is the kind of cpu feature that when we enable it, frequently we > have to do something on the kexec path. > > At a quick skim it looks like the kexec path is using kernel page table > entries and clearing all bits from cr4 except X86_CR4_PAE so I don't > actually expect this change will require anything on the kexec path. >
I have not, no, but as you quite correctly point out that shouldn't affect things.
We should also change the kernel to start clean with CR4 -- the purpose of CR4 is to indicate which CPU features the OS is opting into.
I think we do on x86-64 but not on x86-32 at the moment.
This is an unrelated problem, though, and can be addressed later.
-hpa
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