Re: [PATCH v2 02/22] ieee1275: claim more memory

[Patrick Steinhardt]

On Thu, Jul 15, 2021 at 11:51:04PM +0200, Daniel Kiper wrote:
> CC-in a few people who can be interested in this...
> 
> On Wed, Jun 30, 2021 at 06:40:11PM +1000, Daniel Axtens wrote:
> > On powerpc-ieee1275, we are running out of memory trying to verify
> > anything. This is because:
> >
> >  - we have to load an entire file into memory to verify it. This is
> >    extremely difficult to change with appended signatures.
> >  - We only have 32MB of heap.
> >  - Distro kernels are now often around 30MB.
> >
> > So we want to claim more memory from OpenFirmware for our heap.
> 
> AFAICT it is common problem in the GRUB right now. Please take a look at
> [1], [2]. It would be nice to find general solution for all. Of course
> if possible. So, if somebody could take a look at memory management in
> the GRUB and propose a solution for the problem that would be perfect.
> Any volunteers?
> 
> Daniel
> 
> [1] https://lists.gnu.org/archive/html/grub-devel/2020-06/msg00009.html
> [2] https://lists.gnu.org/archive/html/grub-devel/2021-01/msg00031.html

I think that my [1] should solve the issue generically. Instead of
bumping any of the static limits we have in place, we just drop them
altogether in favor of dynamically requesting additional EFI regions
whenever we realize that the currently mapped regions cannot satisfy our
needs. Like this, we can lower the initially requested regions, but
scale them to the specific needs if need be.

I had planned to revisit this patch series much earlier, but somehow I
didn't yet find the time. Any comments on my approach would be welcome
though, and if we agree that this may be a viable route to go down then
I'd be happy to further pursue it.

Patrick

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