linux-kernel - Re: [PATCH] x86: don't ever patch back to UP if we unplug cpus.

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Message-ID: <877gtmm24m.fsf@rustcorp.com.au>
Date:	Mon, 30 Jul 2012 11:38:57 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	x86@...nel.org, LKML <linux-kernel@...r.kernel.org>,
	Paul McKenney <paul.mckenney@...ibm.com>
Subject: Re: [PATCH] x86: don't ever patch back to UP if we unplug cpus.

On Fri, 27 Jul 2012 13:28:29 -0700, Suresh Siddha <suresh.b.siddha@...el.com> wrote:
> 	if (!noreplace_smp && (num_present_cpus() == 1 || setup_max_cpus <= 1))
> 
> also, to be consistent with other checks, may be just use
> "num_possible_cpus() == 1" check instead of "setup_max_cpus <= 1".

Actually, if you specify "maxcpus=1" on the kernel command line,
you get num_possible_cpus() == 4, even though only one gets online.

So the setup_max_cpus check is in fact correct here.

Thanks!
Rusty.
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