On 10/03/2018 03:56 PM, Jens Wiklander wrote:
On Wed, Oct 3, 2018 at 3:31 PM, Jorge Ramirez-Ortiz jramirez@baylibre.com wrote:
On 10/03/2018 03:17 PM, Jens Wiklander wrote:
On Wed, Oct 3, 2018 at 2:27 PM, Jorge Ramirez-Ortiz jramirez@baylibre.com wrote:
I am upstreaming TF-A support for the Renesas R-car gen3 platforms [1].
In order to prevent the boot cpu from being switched off (hotpluged) I am having to work around the fact that OPTEE_OS does not support MIGRATE_INFO_TYPE or MIGRATE_INFO_UP_CPU.
Why should OP-TEE care about that?
the boot cpu boots OP-TEE; when OP-TEE has migration requirements the boot cpu must not be hot-plugged.
This sounds a bit odd, what in OP-TEE makes the boot cpu so special?
Isn't it rather the SoC that has this requirement? If so perhaps this restriction belongs in the PCSI implementation instead?
yes I think this must be it (I suspected this to be the case but after this thread I am convinced that this must be the situation); the rcar-gen3 switches off everything when suspending so when resuming it must always start TF-A with a well known core (the boot cpu always follows the cold boot path before resuming the other cores via the warm boot path)
So OP-TEE in away should care about implementing those interfaces (unless every OP-TEE ever created is guaranteed to have no migration restrictions).
Trying to predict what every fork of OP-TEE will ever do is not easy so I'm sticking to upstream OP-TEE.
Its SPD at TF-A level [2] returns that the TrustedOS if fully MP aware and has not special requirements for migration.
Isn't that true for upstream OP-TEE?
? but what happens if the user is working with a non-upstream OP-TEE? The way TF-A has been written hard-codes the requirement of an OP-TEE with no migration restrictions.
We try to not make it harder that necessary for the forks, but if there's a conflicts of interests it's upstream that matters.
IMO the code at this level should be generic and always query. why dont you see it this way?
So far I'm not convinced that it's needed, but I'll try to keep an open mind.
maybe it is only ATF that needs changing to allow the platform to be queried about migration requirements ok makes sense. thanks !