Messages in this thread | | | Date | Tue, 25 Feb 2014 12:35:24 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86: set Pentium M as PAE capable |
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On Tue, Feb 25, 2014 at 02:45:57AM -0800, H. Peter Anvin wrote: > On 02/24/2014 10:01 PM, Chris Bainbridge wrote: > >Pentium M is PAE capable but does not indicate so in the CPUID response. > >This is an issue now that some distributions are no longer shipping > >non-PAE kernels (those distributions no longer boot on Pentium M). This > >small patch fixes the issue by forcing the PAE capability on Pentium M. > > > >For more discussion see https://bugs.launchpad.net/baltix/+bug/930447 > > > > 1. This patch doesn't match the discussion in the link. > 2. You would have to also enable this in the cpu testing code in > arch/x86/boot. > 3. At the very least we need to print a serious warning that the CPU > is being run outside its specifications. I have no personal > information about why this CPUID bit was disabled, but it could be > that it was discovered in testing that it didn't work correctly in > all circumstances (e.g. high temperature.) This is very much "use > at your own risk..."; you could get data corruption or even > hardware damage. > > We should probably also taint the kernel.
Right, I was about to say that. And since there's no special bit for running "out-of-spec", we could probably repurpose
TAINT_UNSAFE_SMP - 'S' - SMP with CPUs not designed for SMP.
to
TAINT_UNSAFE_OUT_OF_SPEC (the letter S fits still) and add that taint everytime we're enforcing functionality against doctor's orders, so to speak. :-)
Hmm.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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