Comment 3 for bug 1568952

------- Comment From <email address hidden> 2016-04-12 07:47 EDT-------
(In reply to comment #8)
> Hello,
>

Hi Louis,
> I am not against the modification but would like to understand better the
> rationale behind this. According to the kernel doc we have :

The rationale behind moving from maxcpus=1 to nr_cpus=1 is to reduce
the memory consumption in kdump kernel. nr_cpus is a hard limit that
has an impact on the (kdump) kernel memory consumption,
while it is not the case with maxcpus=1, as we can theoretically hotplug cpus
with maxcpus=1 (not something we would be needing for kdump).

> maxcpus= [SMP] Maximum number of processors that an SMP kernel
> should make use of. maxcpus=n : n >= 0 limits the
> kernel to using 'n' processors. n=0 is a special case,
> it is equivalent to "nosmp", which also disables
> the IO APIC.
>
> nr_cpus= [SMP] Maximum number of processors that an SMP kernel
> could support. nr_cpus=n : n >= 1 limits the kernel to
> supporting 'n' processors. Later in runtime you can not
> use hotplug cpu feature to put more cpu back to online.
> just like you compile the kernel NR_CPUS=n
>
> I personally would be inclined to use maxcpus=0 and totally disable SMP but
> I am opened to other options.
>

As for maxcpus=0, I am not really sure if powerpc supports maxcpus=0 / nosmp
currently.

Thanks
Hari