Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: 2023-02-14 20:19:23
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On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote:
On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf [off-list ref] wrote:quoted
On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daudé wrote:quoted
Can you update the documentation along? Currently we have: /* * Called from the idle thread for the CPU which has been shutdown. * * Note that we disable IRQs here, but do not re-enable them * before returning to the caller. This is also the behaviour * of the other hotplug-cpu capable cores, so presumably coming * out of idle fixes this. */void __ref cpu_die(void) { idle_task_exit(); local_irq_disable(); __asm__ __volatile__( " movi a2, cpu_restart\n" " jx a2\n"); BUG(); } Hm, not only is the comment wrong, but it seems to be branching to cpu_restart? That doesn't seem right at all.Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart' loops there until a call to 'boot_secondary' releases it, after which it goes to '_startup'. So it is a restart, but not immediate.
Ah, I see. That sounds similar to what Xen does. -- Josh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel