On Thu, Dec 10, 2015 at 11:45:36AM +0530, Bharata B Rao wrote:
> Prevent guests from booting with CPU topologies that have partially
> filled CPU cores or can result in partially filled CPU cores after CPU
> hotplug like
>
> -smp 15,sockets=1,cores=4,threads=4,maxcpus=16 or
> -smp 15,sockets=1,cores=4,threads=4,maxcpus=17 or
>
> Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> ---
> vl.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/vl.c b/vl.c
> index 525929b..e656f53 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1252,6 +1252,19 @@ static void smp_parse(QemuOpts *opts)
> smp_cores = cores > 0 ? cores : 1;
> smp_threads = threads > 0 ? threads : 1;
>
> + if (smp_cpus % smp_threads) {
> + error_report("cpu topology: "
> + "smp_cpus (%u) should be multiple of threads (%u)",
> + smp_cpus, smp_threads);
> + exit(1);
> + }
> +
> + if (max_cpus % smp_threads) {
> + error_report("cpu topology: "
> + "maxcpus (%u) should be multiple of threads (%u)",
> + max_cpus, smp_threads);
> + exit(1);
> + }
> }
Adding this seems like it has a pretty high chance of causing regression,
ie preventing previously working guests from booting with new QEMU. I
know adding the check makes sense from a semantic POV, but are we willing
to risk breaking people with such odd configurations ?
Regards,
Daniel
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