RE: [Xen-devel] [PATCH] supporting non-NX/XD capable processors on x86_64 xenlinux

["Nakajima, Jun" <jun.nakajima@xxxxxxxxx>]

Jerone Young wrote:
> This is identical to the patch Scott Parish sent awhile back. Jun you
> said that this was not a good way of going about fixing this (actually
> it was kind of toward another problem ...but I think we were also
> trying to get x86-64 xen to just boot at the time). I guess this is
> the best way then?
As far as I remember, it was not root caused at that time, then I was
not sure it was the right fix... 

The problem is that __PAGE_KERNEL is used by several places, such as
ioremap_change_attr
xen_contig_memory
blkback.c:  dispatch_probe

And __PAGE_KERNEL on native x86_64 Linux has always NX on:
#define __PAGE_KERNEL \
        (_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED |
_PAGE_NX)

So, actually we have two options to fix this:
1. Change __PAGE_KERNEL => _KERNPG_TABLE
2. The above (i.e. & __supported_pte_mask)

I don't have particular preference, but the latter one's change is
smaller, and it can fix other places (that are using the attrributes
derived from __PAGE_KERNEL). But the former one is cleaner to me. If
people agree, I can make such a patch.

Jun
---
Intel Open Source Technology Center

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