Re: [Qemu-ppc] [Qemu-devel] [PATCH] pseries: do not allow memory-less/cpu-less NUMA node

[Daniel P . Berrangé]

On Fri, Aug 30, 2019 at 06:13:45PM +0200, Laurent Vivier wrote:
> When we hotplug a CPU on memory-less/cpu-less node, the linux kernel
> crashes.
> 
> This happens because linux kernel needs to know the NUMA topology at
> start to be able to initialize the distance lookup table.
> 
> On pseries, the topology is provided by the firmware via the existing
> CPUs and memory information. Thus a node without memory and CPU cannot be
> discovered by the kernel.
> 
> To avoid the kernel crash, do not allow to start pseries with empty
> nodes.

This describes one possible guest OS. Is there any reasonable chance
that a non-Linux guest might be able to handle this situation correctly,
or do you expect any guest to have the same restriction ?

> Signed-off-by: Laurent Vivier <address@hidden>
> ---
>  hw/ppc/spapr.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)

Regards,
Daniel
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