linux-kernel - What clockevents are needed to boot properly?

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Date:   Sun, 7 Mar 2021 16:10:07 -0800
From:   Theodore Dubois <tblodt@...oud.com>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de
Subject: What clockevents are needed to boot properly?

I'm playing around with a new kernel arch and running into problems with properly configuring the clockevents, especially with SMP. Without SMP you can easily set up a clockevents masked to cpu 0, and this seems to work fine. But on SMP this fails silently: high-res timers created on cpu != 0 never fire.

The obvious next thing to try would be to set the mask of the clockevents to cpu_possible_mask, but this silently fails as well: the clockevents just doesn't get used at all. There seem to be a lot of drivers in the tree that do this, I'm not sure why it works for those.

Do you have to register a new clockevents for each CPU? I can't find a lot of information on this.

~Theodore