On 12/11/24 17:27, Sughosh Ganu wrote:
On Wed, 11 Dec 2024 at 21:50, Patrice CHOTARD patrice.chotard@foss.st.com 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.
I don't think that this patch should be reverted. If the said platform has a reserved memory region above ram_top, I would suggest to either a) move the ram_top on this platform so that the op-tee region gets marked as no-map in the lmb memory map, or b) do not use the lmb
In my explanation above, i indicated that before this commit, this area was marked as LMB_NOMAP in the lmb memory map by boot_fdt_add_mem_rsv_regions(). this is exactly what you described in the possible solution "a)".
But now with this commit, as lmb_add_memory() is called in lmb_init() the area above ram_top is marked LMB_NOOVERWRITE. Then later, boot_fdt_add_mem_rsv_regions() is executed, but the area above ram_top can't be marked as LMB_NOMAP as previously because it's already marked LMB_NOOVERWRITE.
memory map to configure the MMU -- can the MMU configuration logic not read the DT to get which regions are to be marked as no-map?
As far as the lmb module is concerned, it is being told through this commit to not consider memory above ram_top for allocations, which is not an incorrect thing imo.
That's the case, we don't consider memory above ram_top for allocations, we only marked it with LMB_NOMAP.
Thanks Patrice
-sughosh
Patrice