[PATCH 6/6] arm: mach-k3: Move DRAM address of ATF for AM62/AM62a

[Andrew Davis]

On 2/15/24 2:06 AM, Francesco Dolcini wrote:
> Hello Andrew,
> thanks for this series.
> 
> On Wed, Feb 14, 2024 at 10:30:09AM -0600, Andrew Davis wrote:
>> The current address of TF-A in DRAM is just below the 512MB address line.
>> This means if the DRAM in a system is 512MB then TF-A is right at the
>> end of memory which is often reused, for instance U-Boot relocates itself
>> here. If a system has less than 512MB then that system wouldn't work at
>> all as TF-A would fail to load.
> 
> Do you expect issue with system with exactly 512MB of RAM? We have such
> a board available and this is something that was not on our radar.

The issues with exactly 512MB are much less than the systems with less.
Mostly small software issues like the one you work around below with
U-Boot relocation.

> 
> The way we handle this is with `verdin-am62.c:board_get_usable_ram_top()`
> 

The point of this patch is to avoid the need for workarounds like that in
the first place.

> There is also some other reserved memory just before the 512MB limit,
> not just the TF-A.

This series prepares for also moving OP-TEE at some point (which will be
a bit more involved as it still needs to be made position independent).
The other reserved memory is mostly for remoteproc firmware which should
be made dynamic instead of hard-coding memory carve-outs for their use.

Andrew

> 
> Francesco
>