From bf23f24bab6b6aaa63e16715dbb78a31b7fe0dc4 Mon Sep 17 00:00:00 2001 From: Peter Krempa Date: Tue, 4 Apr 2017 16:02:21 +0200 Subject: [PATCH] docs: Document limitation of maximum vcpu count used with qemu requires that the topology equals to the maximum vcpu count. Document this along with the API to set maximum vcpu count and the XML element. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1426220 (cherry picked from commit 4661a1868bb4d918e43ed96c4ae14f5ecd37b3f7) --- docs/formatdomain.html.in | 5 ++++- src/libvirt-domain.c | 3 ++- tools/virsh.pod | 3 ++- 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index aae5e9c071..b1e38f00e4 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1401,7 +1401,10 @@ virtual CPU provided to the guest. Three non-zero values have to be given for sockets, cores, and threads: total number of CPU sockets, number of cores per - socket, and number of threads per core, respectively. + socket, and number of threads per core, respectively. Hypervisors may + require that the maximum number of vCPUs specified by the + cpus element equals to the number of vcpus resulting + from the topology.
feature
The cpu element can contain zero or more diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index 4670c54e5e..310b91b373 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -7010,7 +7010,8 @@ virDomainSetVcpus(virDomainPtr domain, unsigned int nvcpus) * CPU limit is altered; generally, this value must be less than or * equal to virConnectGetMaxVcpus(). Otherwise, this call affects the * current virtual CPU limit, which must be less than or equal to the - * maximum limit. + * maximum limit. Note that hypervisors may not allow changing the maximum + * vcpu count if processor topology is specified. * * If @flags includes VIR_DOMAIN_VCPU_GUEST, then the state of processors is * modified inside the guest instead of the hypervisor. This flag can only diff --git a/tools/virsh.pod b/tools/virsh.pod index 9a52d67163..d1030808a3 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -2477,7 +2477,8 @@ marked as hotpluggable. The I<--maximum> flag controls the maximum number of virtual cpus that can be hot-plugged the next time the domain is booted. As such, it must only be used with the I<--config> flag, and not with the I<--live> or the I<--current> -flag. +flag. Note that it may not be possible to change the maximum vcpu count if +the processor topology is specified for the guest. =item B I I [I<--enable>] | [I<--disable>] [[I<--live>] [I<--config>] | [I<--current>]] -- GitLab