Re: [v2 2/4] xen/arm32: head: Don't map too much in boot_third

[Julien Grall <julien@xxxxxxx>]

Hi Bertrand,

On 04/07/2023 15:12, Bertrand Marquis wrote:
> > On 29 Jun 2023, at 22:11, Julien Grall <julien@xxxxxxx> wrote:
> >
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > At the moment, we are mapping the size of the reserved area for Xen
> > (i.e. 2MB) even if the binary is smaller. We don't exactly know what's
> > after Xen, so it is not a good idea to map more than necessary for a
> > couple of reasons:
> >     * We would need to use break-before-make if the extra PTE needs to
> >       be updated to point to another region
> >     * The extra area mapped may be mapped again by Xen with different
> >       memory attribute. This would result to attribute mismatch.
> >
> > Therefore, rework the logic in create_page_tables() to map only what's
> > necessary. To simplify the logic, we also want to make sure _end
> > is page-aligned. So align the symbol in the linker and add an assert
> > to catch any change.
> The last 2 sentences actually belongs to patch 1 and have been copied
> here. Please remove them on commit as alignment of _end is not in
> this patch.
Good point. I have removed them.

> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
> With commit message fixed on commit:
> Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
Thanks!

Cheers,

--
Julien Grall