[fedora-virt] Re: [PATCH] xen: do not set NX bit when making initial pagetables readonly
On Fri, 2009-01-30 at 10:56 -0800, Jeremy Fitzhardinge wrote:
Ian Campbell wrote:
> __supported_pte_mask has not been correctly configured at this point
> and Xen prevents us from using the NX bit if the hardware does not
> support it. Some BIOSes seem to offer the option to disable NX.
>
Could we sniff EFER and update __supported_pte_mask accordingly?
Perhaps, we might also have to handle the various noexec= command line
options? I don't suppose they matter so much in a guest though.
The equivalent native seems to use _KERNPG_TABLE as well (e.g.
head_64.S) -- is there something later on which comes along and tries to
apply the NX bit to those pages which didn't get it at start of day?
Ian.