Re: [RFC PATCH 2/4] x86: use dmi check to treat disabled cpus as hotplug cpus.

From: Valdis . Kletnieks
Date: Tue Jan 12 2010 - 11:18:11 EST


On Mon, 11 Jan 2010 19:13:32 PST, Linus Torvalds said:

> - only use that flat apic mode when you _know_ that you absolutely will
> never have more than 8 cpu's. Ie when CONFIG_NR_CPUS <= 8 (or, with
> 1/3, when nr_cpu_ids <= 8) and/or when <= 8 CPU's were detected, and
> CPU hotplug is disabled entirely.

OK, I'll bite - how do you build an X86-64 kernel that doesn't have
CONFIG_HOTPLUG_CPU selected? Try as I might, even if I have PM_SLEEP=n,
PM_SLEEP_SMP insists on being set, and then selecting HOTPLUG_SMP. For the
record, I do *not* need/desire S2R, S2D, 'suspend', or similar functionality.

Is there some subtle reason why PM_SLEEP_SMP has to be on even without PM_SLEEP?

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