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Re: [PATCH] Fix i486 suspend to disk CR4 oops

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From: H. Peter Anvin
Subject: Re: [PATCH] Fix i486 suspend to disk CR4 oops
Date: Monday, August 18, 2008 - 3:10 pm

Pavel Machek wrote:

Theoretically it can, but that means no features are enabled, so there 
is no need to enable the features.

The real question is if the following can happen: can it be such that we 
want CR4 to be zero in a situation where CR4 is nonzero to start out with?

The main bit in CR4 that could be set that we wouldn't want set would be 
CR4.PAE, so this could happen if there is a CPU with CR4.PAE but none of 
the other CR4 bits that we would normally set unconditionally.

I'm pretty sure this can't happen on any physical CPUs, since all 
physical CPUs supporting PAE would also support DE, MCE, and PGE.  It 
could possibly happen on a virtual CPU, although it is of course 
extremely unlikely we'd get there with CR4 not zero to start out with.

Still, it is at least theoretically wrong.

	-hpa
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Messages in current thread:
[PATCH] Fix i486 suspend to disk CR4 oops, David Fries, (Sun Aug 17, 9:03 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Maciej W. Rozycki, (Sun Aug 17, 9:14 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, H. Peter Anvin, (Sun Aug 17, 9:35 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Andi Kleen, (Sun Aug 17, 11:04 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, H. Peter Anvin, (Sun Aug 17, 11:34 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Ingo Molnar, (Sun Aug 17, 11:41 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Andi Kleen, (Sun Aug 17, 11:42 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, H. Peter Anvin, (Sun Aug 17, 11:45 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Pavel Machek, (Mon Aug 18, 2:15 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Rafael J. Wysocki, (Mon Aug 18, 3:16 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, David Fries, (Mon Aug 18, 5:58 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Ingo Molnar, (Mon Aug 18, 6:25 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Maciej W. Rozycki, (Mon Aug 18, 7:38 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Maciej W. Rozycki, (Mon Aug 18, 7:41 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Dave Jones, (Mon Aug 18, 8:24 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Lennart Sorensen, (Mon Aug 18, 9:04 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Dave Jones, (Mon Aug 18, 10:17 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, H. Peter Anvin, (Mon Aug 18, 10:32 am)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Pavel Machek, (Mon Aug 18, 3:02 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, Pavel Machek, (Mon Aug 18, 3:04 pm)
Re: [PATCH] Fix i486 suspend to disk CR4 oops, H. Peter Anvin, (Mon Aug 18, 3:10 pm)
Re: [PATCH] i486 CR4 oops, no_console_suspend, David Fries, (Mon Aug 18, 8:37 pm)
Re: [PATCH] i486 CR4 oops, no_console_suspend, Ingo Molnar, (Tue Aug 19, 2:34 am)
Re: [PATCH] i486 CR4 oops, no_console_suspend, H. Peter Anvin, (Tue Aug 19, 9:07 am)
Re: [PATCH] i486 CR4 oops, no_console_suspend, David Fries, (Wed Aug 20, 9:17 pm)
Re: [PATCH] i486 CR4 oops, no_console_suspend, H. Peter Anvin, (Wed Aug 20, 10:37 pm)