Re: [PATCH] efi/arm64: efistub: don't abort if base of DRAM is occupied

[Mark Salter <msalter-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Tue, 2014-07-15 at 15:49 +0100, Leif Lindholm wrote:
> On Tue, Jul 15, 2014 at 10:23:26AM -0400, Mark Salter wrote:
> > On Tue, 2014-07-15 at 14:54 +0100, Leif Lindholm wrote:
> > > On Tue, Jul 15, 2014 at 09:11:00AM -0400, Mark Salter wrote:
> > > > On Tue, 2014-07-15 at 11:02 +0100, Leif Lindholm wrote:
> > > > > > @@ -273,6 +282,10 @@ static void __init free_boot_services(void)
> > > > > >                       continue;
> > > > > >               }
> > > > > >  
> > > > > > +             /* Don't free anything below kernel */
> > > > > > +             if (md->phys_addr < PHYS_OFFSET)
> > > > > > +                     continue;
> > > > > > +
> > > > > 
> > > > > Is the spin table area really allocated as BOOT_SERVICES_*?
> > > > 
> > > > No. It is EFI_RESERVED_TYPE. But if UEFI is allowed below the kernel,
> > > > then there could be BS code/data memory which we'd want to ignore.
> > > 
> > > Well, if it is boot service code/data - then there is no need for us
> > > to keep it around after ExitBootServices().
> > 
> > One would think, but EFI has proven to be less than strictly compliant
> > in that regard in the past. I'm inclined to keep the boot services
> > around until after SetVirtualAddressMap just in case.
> 
> But the function you add this clause to will still throw away all boot
> services code/data regions - just with this modification it skips
> those that happen to lie lower in the address space than the kernel.
> 
> (And I do agree with Mark R here - let's not work around bugs that
> don't exist yet.)
> 

I'm not sure if they still exist or not, but on Foundation, I saw a
crash in SetVirtualAddressMap unless I kept BS regions around.