Hi Julius
-----Original Message----- From: Julius Werner jwerner@chromium.org Sent: 11 September 2019 03:00 To: Dan Handley Dan.Handley@arm.com Cc: tf-a@lists.trustedfirmware.org Subject: Re: [TF-A] SMC to intentionally trigger a panic in TF-A
Hi Dan,
Whoops, sorry, this fell through the cracks for me since I wasn't on the to: line. Thanks for your response!
You're welcome.
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However, I think there might already be support for what you need. PSCI is
part of the standard service and the function SYSTEM_RESET2 allows for both architectural and vendor-specific resets. The latter allows for vendor- specific semantics, which could include crashing the firmware as you suggest.
Chrome OS could specify what such a vendor-specific reset looks like and
each Chromebook's platform PSCI hooks could be implemented accordingly.
Right, but defining a separate vendor-specific reset type for each platform is roughly the same as defining a separate SiP SMC for each of them. It's the same problem that the SMC/PSCI spec and the TF repository layout is only designed to deal with generic vs. SoC-vendor-specific differentiation. If the normal world OS needs a feature, we can only make it generic or duplicate it across all vendors running that OS.
Not quite. The SiP SMC range is already populated with existing SiP stuff whereas the vendor-specific bits of the reset_type in PSCI SYSTEM_RESET2 is unlikely to contain much/any vendor specific stuff. Therefore Chrome OS could define something "generic to Chrome OS" in this space that Chromebooks could implement. There could also be a Chrome OS specific folder for this kind of functionality that Chromebooks pull in.
Alternatively, this could potentially be defined as an additional
architectural reset. This would enable a generic implementation but would require approval/definition by Arm's Architecture team. Like me they might have concerns about this being defined at a generic architectural level.
Yes, I think that would be the best option. Could you kick off that process with the Architecture team? Or tell me who I should talk to about this?
OK, I'll fire off an email internally now and then either put you in contact or let you know how it goes.
Regards
Dan.
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