Re: [PATCH v3 2/2] efi: Free malloc regions on exit

[Alexander Graf]

On 08/29/2017 08:25 PM, Leif Lindholm wrote:
> On Tue, Aug 29, 2017 at 06:00:35PM +0200, Alexander Graf wrote:
> > When we exit grub, we don't free all the memory that we allocated earlier
> > for our heap region. This can cause problems with setups where you try
> > to descend the boot order using "exit" entries, such as PXE -> HD boot
> > scenarios.
> >
> > Signed-off-by: Alexander Graf <address@hidden>
> Really happy to see this, but repeating a comment here from irc:
> This deals with the biggest problem with returning to UEFI - GRUB
> allocates 25% of available RAM, which before this patch we don't
> release. However, various operations may allocate EFI memory directly,
> and those allocations are not currently being tracked.
>
> If further allocations could be tracked from
> grub_efi_allocate_pages_real, these could be unwound in
> _memory_fini(). Those can safely be allocated from the heap.

I'm using pool allocations now which *usually* go into a malloc like 
pool on the UEFI side anyway, hence I don't think we should complicate 
the logic even more and differentiate between heap and non-heap 
allocations. I'll just add all allocations from 
efi_allocate_pages_real() to the list and free them on exit - that 
should be safest.


Alex