Hi Sandeep
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Sandeep Tripathy via TF-A Sent: 03 December 2019 16:59
Hi, system shutdown or system reset PSCI calls are invoked by the last core in the system.
That may be the case in practice but these functions can be called by any core in the system at any time, not just the last core.
PSCI lib does not do cache flush for the last core /cluster and does not follow the core / cluster power down sequence.
Correct. Not only that, it doesn't do anything with the other cores in the system that may be running at that time.
This may cause issue in a system if the system is not standalone one ie if the system is a slave or node in a bigger system with other coherent masters/PEs.
What issue specifically? Are the other coherent masters expecting to have the same view of the node's memory that the node had prior to calling system off/suspend? If so, then the node is not really independent to the wider system and system off/reset are probably not the right calls to use. Perhaps SYSTEM_SUSPEND is what you're looking for? That function requires all other cores to be off before the call and will perform cache maintenance on the last core.
Please suggest if the PSCI spec expected 'shutdown/reset/reset2' to deliberately skip the core/cluster shutdown sequence.
Yes, the spec was deliberately relaxed between version 0.2 and 1.0 to allow implementations to just "pull the plug" since there would be no observable difference to the normal world caller between this behaviour and attempting to shutdown cleanly, which would be difficult and inherently racy anyway.
Otherwise in case it makes sense following is a patch to take care of this. https://review.trustedfirmware.org/#/c/TF-A/trusted-firmware-a/+/2364/ issue: https://developer.trustedfirmware.org/T566
Thanks but I don't think we want this.
Regards
Dan.
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