[PATCH] lmb: prohibit allocations above ram_top even from same bank

[Sughosh Ganu]

On Fri, 13 Dec 2024 at 00:48, Tom Rini <trini at konsulko.com> wrote:
>
> On Wed, Dec 11, 2024 at 05:18:28PM +0100, Patrice CHOTARD wrote:
>
> >
> >
> > On 12/7/24 16:57, Tom Rini wrote:
> > > On Mon, 02 Dec 2024 12:36:24 +0530, Sughosh Ganu wrote:
> > >
> > >> There are platforms which set the value of ram_top based on certain
> > >> restrictions that the platform might have in accessing memory above
> > >> ram_top, even when the memory region is in the same DRAM bank. So,
> > >> even though the LMB allocator works as expected, when trying to
> > >> allocate memory above ram_top, prohibit this by marking all memory
> > >> above ram_top as reserved, even if the said memory region is from the
> > >> same bank.
> > >>
> > >> [...]
> > >
> > > Applied to u-boot/master, thanks!
> > >
> > Hello
> >
> > This patch is breaking the boot on STM32MP135F-DK.
> >
> > On this platform, we got an area above gd->ram_top,
> > this area, reserved for OPTEE, is tagged with LMB_NOMAP in boot_fdt_add_mem_rsv_regions().
> >
> > Since this commit 1a48b0be93d4 ("lmb: prohibit allocations above ram_top even from same bank"),
> > this area is no more tagged as LMB_NOMAP, because it's previously been
> > tagged with LMB_NOOVERWRITE in lmb_add_memory().
> >
> > By not being tagged LMB_NOMAP, the MMU configuration is impacted and leads to a panic.
> >
> > I suggest to revert this patch.
>
> Hi Patrice. Can you please re-test current top of tree? I believe Sam's
> series should resolve this problem as well. Thanks!

Tom, that won't happen. This is a separate issue from what is being
fixed by Sam's series.

Patrice, please let me know if the hang is being fixed by the change
that I had suggested earlier in this thread. For some reason I don't
see a hang on the DK2 board despite the board having a similar memory
map of memory being reserved for the op-tee image above ram_top with
no-map property.

-sughosh

>
> --
> Tom