Re: [PATCH 2/2] xen/arm: Handle reserved heap pages in boot and heap allocator

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 1 Sep 2022, Julien Grall wrote:
> Hi Stefano,
> 
> On 01/09/2022 18:08, Stefano Stabellini wrote:
> > > > Also, what happen with UEFI? Is it easy to guarantee the region will not
> > > > be used?
> > > 
> > > For now I think it is not easy to guarantee that, do you have some ideas
> > > in mind? I think I can follow this in above follow-up series to improve
> > > things.
> > 
> > For clarity, are we worried that the region is used by the bootloader
> > for other things? For instance U-Boot or Tianocore placing some
> > firmware tables inside the range specified for xenheap?
> 
> Yes. I think it would be difficult for an admin to figure out which regions
> are used. Although they are likely (?) going to be static for a given
> UEFI/U-boot build.
> 
> My major concern is such bug can be very difficult to root cause because we
> have no safety in Xen. The most likely symptom would be random corruption.

Thanks for the clarification. Yeah, I think we'll have to do some
"creative thinking" to figure out a solution to this issue. I wonder if
U-boot or Tianocore have some sort of API (or build-time data) to know
the unavailable ranges.

In any case, I think we can postpone to after the release.