RE: [tip:x86/urgent] x86-64, init: Do not set NX bits on non-NXcapable hardware

From: Yuhong Bao
Date: Sat May 11 2013 - 01:57:27 EST


(resending as plaintext)
> During early init, we would incorrectly set the NX bit even if the NX
> feature was not supported. Instead, only set this bit if NX is
> actually available and enabled. We already do very early detection of
> the NX bit to enable it in EFER, this simply extends this detection to
> the early page table mask.
AFAIK the only production x86-64 processor that don't support NX that I know of is the original Nocona D0 stepping.
Must more common are the problem of BIOSes disabling the NX feature.


Yuhong Bao --
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