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

[Patrice CHOTARD]

On 12/12/24 20:50, Sughosh Ganu wrote:
> 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.

Hi All

I confirm, Sam's series didn't help here as Sughosh said.

> 
> 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.

On my side i didn't see the issue on STM32MP157C-DK2 board, but 
i got it systematically on STM2MP135F-DK.

Your suggested patch is fixing the hang observed, i will send a patch.

Thanks all ;-)

Patrice


> 
> -sughosh
> 
>>
>> --
>> Tom