Re: [PATCH v6 2/4] hw/arm/virt: Consider SMP configuration in CPU topology

[Andrew Jones]

On Wed, Apr 20, 2022 at 10:24:46PM +0800, Gavin Shan wrote:
...
> With amend to the command lines, the following one is used and below error
> is raised from the test. The error is mentioned in the commit log in
> PATCH[v7 2/4].
> 
>     -machine smp.cpus=2                                   \
>     -numa node,nodeid=0,memdev=ram -numa node,nodeid=1    \
>     -numa cpu,node-id=1,thread-id=0                       \
>     -numa cpu,node-id=0,thread-id=1
> 
>     qemu-system-aarch64: -numa cpu,node-id=0,thread-id=1: no match found
>     (reported from hw/core/machine.c::machine_set_cpu_numa_node())
> 
> After the changes to virt_possible_cpu_arch_ids() is applied, "thread-id=1"
> isn't valid any more. The CPU topology becomes like below. Note that
> mc->smp_props.prefer_sockets is true on arm/virt machine.

prefer_sockets is only true for mach-virt 6.1 and older. It's false for
6.2 and later.

Thanks,
drew

> 
>     index    socket   cluster    core    thread
>     --------------------------------------------
>       0        0        0         0        0
>       1        1        0         0        0
> 
> With the amended command lines, the topology changes again so
> that "thread-id=1" is valid:
> 
>     index    socket   cluster    core    thread
>     --------------------------------------------
>       0        0        0         0        0
>       1        0        0         0        1
> 
> It should be ok to split the test/qtest/aarch64_numa_cpu() changes into
> a separate patch and put it before this one. In that case, the specified
> smp.{socket, cluster, core, threads} isn't used by arm/virt machine yet,
> and 'thread-id=2' should be still valid. Lets do this if I need post v8.
> Otherwise, I guess it's also fine to squash the test/qtest/aarch64_numa_cpu()
> changes into PATCH[2/4], as we're doing.
> 
> > 
> > > 
> > > 
> > > > >            "-numa node,nodeid=0,memdev=ram -numa node,nodeid=1 "
> > > > >            "-numa cpu,node-id=1,thread-id=0 "
> > > > >            "-numa cpu,node-id=0,thread-id=1");
> 
> Thanks,
> Gavin
>