Re: [Qemu-devel] [PATCH] vl.c: Check max_cpus limit instead of smp_cpus

[Peter Maydell]

On 7 May 2014 23:20, Andreas Färber <address@hidden> wrote:
> Am 07.05.2014 23:48, schrieb Peter Maydell:
>> This is confusing. What is max_cpus
>
> Specified via -smp, defaults to actual CPUs.

I thought that was smp_cpus ...

>> and why do we not
>> just set max_cpus = machine->max_cpus ?
>
> For the PC, machine->max_cpus specifies the technical (APIC/ACPI/...)
> upper limit, whereas -smp limits it to saner values.
>
> If you think KVM, then many machines today will have less than the
> maximum number of CPUs and you may want to run multiple VMs and you may
> not want their vCPUs competing too much for existing CPUs, so a limit
> makes sense.

That would imply that we want
  max_cpus = MIN(command_line_max_cpus, machine->max_cpus);

thanks
-- PMM