[PATCH] arm: apple: Fix mem layout

[Mark Kettenis]

> From: Simon Glass <sjg at chromium.org>
> Date: Wed, 23 Mar 2022 03:59:58 -0600
> 
> Hi Mark,
> 
> On Mon, 21 Mar 2022 at 15:41, Mark Kettenis <kettenis at openbsd.org> wrote:
> >
> > The current approach for setting the environment variables that
> > describe the memory layout runs the risk of overlapping with
> > reserved memory regions. Use the lmb code to derive the addresses
> > for these variables instead.
> >
> > Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> > ---
> >
> > Another candidate for 2022.04.  Not a regression either, but the
> > current code may end up randomly failing due to address space
> > randomization. The efi_loader bootpath seems to be unaffected, but
> > attempt to load a Linux kernel directly are more likely to fail.
> > Also tested widely by people using the Asahi Linux installer.
> 
> Where is the randomisation happening?

There are a few factors here.  The Apple bootloader loads m1n1 at a
somewhat random address.  And then there are variations in how U-Boot
gets loaded (as a m1n1 payload, chainloaded, running under the m1n1
hypervisor, etc.) that affect which memory ranges end up being
reserved in the DTB by m1n1.  And the variation in firmware between
machines makes the memory map somewhat unpredictable too.

> >  arch/arm/mach-apple/board.c | 32 ++++++++++++++------------------
> >  1 file changed, 14 insertions(+), 18 deletions(-)
> 
> Reviewed-by: Simon Glass <sjg at chromium.org>
>