Re: [v2 4/4] xen/arm: Allow the user to build Xen with UBSAN

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 30/06/2023 07:58, Michal Orzel wrote:
> On 29/06/2023 22:11, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > UBSAN has been enabled a few years ago on x86 but was never
> > enabled on Arm because the final binary is bigger than 2MB (
> > the maximum we can currently handled).
> >
> > With the recent rework, it is now possible to grow Xen over 2MB.
> > So there is no more roadblock to enable Xen other than increasing
> > the reserved area.
> >
> > On my setup, for arm32, the final binaray was very close to 4MB.
> > Furthermore, one may want to enable UBSAN and GCOV which would put
> > the binary well-over 4MB (both features require for some space).
> > Therefore, increase the size to 8MB which should us some margin.
> >
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > ---
> >
> > The drawback with this approach is that we are adding 6 new
> > page-table (3 for boot and 3 for runtime) that are statically
> > allocated. So the final Xen binary will be 24KB bigger when
> > neither UBSAN nor GCOV.
> >
> > If this is not considered acceptable, then we could make the
> > size of configurable in the Kconfig and decide it based on the
> > features enabled.
> >
> >      Changes in v2:
> >          - Fix typoes
> >          - Add Michal's reviewed-by tag
> I cannot see one, so:
Hmmmm, you gave it on v1 but I can't remember why I didn't carry it. 
Anyway...
> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
Thanks!

Cheers,

--
Julien Grall