Re: [PATCH v2] x86/mm: warn on W+x mappings

[Josh Triplett]

On Mon, Oct 12, 2015 at 04:17:54PM +0200, Ingo Molnar wrote:
> * Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Mon, 12 Oct, at 02:49:36PM, Ingo Molnar wrote:
> > > So why not unmap them after bootup? Is there any reason to call into EFI code 
> > > while the system is up and running?
> > 
> > That's where the runtime services code lives. So if you want things like EFI 
> > variables (used by the distro installer, among other things) you need to map the 
> > runtime regions.
> 
> So EFI variables could be queried during bootup and saved on the Linux side.

That wouldn't support writing to EFI variables.  Or using the EFI
capsule update system to update firmware.

- Josh Triplett
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