Re: [Qemu-devel] [patch] Introduce per machine based max_cpu variable

[Anthony Liguori <anthony@codemonkey.ws>]

Jes Sorensen wrote:
>>> Index: qemu/hw/an5206.c
>>> ===================================================================
>>> --- qemu.orig/hw/an5206.c +++ qemu/hw/an5206.c @@ -88,8 +88,9 @@
>>> static void an5206_init(ram_addr_t ram_s } QEMUMachine
>>> an5206_machine = { - "an5206", - "Arnewsh 5206", - an5206_init, -
>>> 512, + .name = "an5206", + .desc = "Arnewsh 5206", + .init =
>>> an5206_init, + .ram_require = 512, + .max_cpus = 1, };
>>>       
>
> Anthony> Your change would be greatly simplified if you defined
> Anthony> max_cpus to be such that it was the maximum number of vcpus -
> Anthony> 1.
>
> Anthony> Then the default value of 0 would be sufficient for most
> Anthony> machine types.
>
> Hi Anthony,
>
> I thought about this, but I think it's a really bad idea. It will
> cause confusion over time and I think it is quite reasonable to
> require all machines to define the maximum number of CPUs they
> support. Thats why I defined the error message so it was quite easy
> for anyone to fixup in case I got one of them wrong.
>
> I really think it's better to do this right than hack it.
>   

If it were 'max_cpu' then the meaning is pretty clear.  On a UP system, 
the max_cpu is 0.

You could also make it max_aps which makes it even more clear.  A UP 
system doesn't have any APs.

The other option is to have max_cpus == 0 be equivalent to max_cpus == 
1.  But don't print anything.  Basically, I don't like the idea of 
modifying every machine definition when they all have almost the exact 
same value for the field.

Regards,

Anthony Liguori