Re: [PATCH 1/5] x86/smpboot: Add the missing description of possible_cpus

From: Dou Liyang
Date: Wed Mar 21 2018 - 01:33:38 EST


Hi Peter,

At 03/20/2018 08:37 PM, Peter Zijlstra wrote:
On Tue, Mar 20, 2018 at 07:04:28PM +0800, Dou Liyang wrote:

+ possible_cpus= [s390,x86_64] Use this to set hotpluggable cpus.
+ This option sets possible_cpus bits in cpu_possible_map.
+ Thus keeping the numbers of bits set constant even if
+ the machine gets rebooted.

That description, esp. the last sentence, doesn't make any kind of sense
to me. What?


Ah, sure enough, I can't be lazy. :-) I stole that from the commit
 3b11ce7f542e ("x86: use possible_cpus=NUM to extend the possible cpus allowed")

How about:

possible_cpus= [s390,x86_64] Set the number of possible CPUs which
are determined by the ACPI tables MADT or mptables by
default. possible_cpus=n : n >= 1 enforces the possible
number to be 'n'.
While nr_cpus is also be set: nr_cpus=m, choice the
minimum one for the number of possible CPUs.

Thank,
dou