[U-Boot] [PATCH 7/6] sunxi: Reserve ATF memory space on A64

[Alexander Graf]

On 13.04.16 21:46, Andre Przywara wrote:
> Hi,
> 
> sorry for the late reply, just found your series here.
> 
> On 30/03/16 16:53, Alexander Graf wrote:
>> On the A64 we usually boot with ATF running in EL3. ATF as it is available
>> today resides in the first 16MB of RAM.
> 
> So this is actually a mistake Allwinner made and which we haven't fixed yet.
> ATF (at least BL3-1, which is the runtime service part we use for the
> A64) should at least run in secure memory, actually in secure SRAM.
> Having it in DRAM is a kludge, unnecessary (it's small enough to reside
> in some SRAM), a waste of memory (it should get along with something
> like 32KB) and also insecure, as long as we don't use the TrustZone
> controller to mark this part of DRAM as secure.
> 
>> So we should make sure we reserve
>> that space in our memory maps.
> 
> I will try to load ATF into one of the SRAM regions the A64 has, and tag
> that as secure. U-Boot shouldn't care about ATF then, we don't need to
> reserve any memory for it - after all those SRAM regions look like some
> kind of MMIO device which we wouldn't touch anyway.

I think that's a great plan moving forward. Is there any way we can
runtime detect this in U-Boot to run with both old and new ATF versions
or should we just break backwards compatibility?


Alex