Re: [libvirt] [PATCH v2] send default USB controller in xml to destination during migration

The default USB controller is not sent to destination as the older versions of libvirt(0.9.4 or earlier as I see in commit log of 409b5f54) didn't support them. For some archs where the support started much later can safely send the USB controllers without this worry. So, send the controller to destination for all archs except x86. Moreover this is not very applicable to x86 as the USB controller has model ich9_ehci1 on q35 and for pc-i440fx, there cant be any slots before USB as it is fixed on slot 1. The patch fixes a bug that, if the USB controller happens to occupy a slot after disks/interfaces and one of them is hot-unplugged, then the default USB controller added on destination takes the smallest slot number and that would lead to savestate mismatch and migration failure. Seen and verified on PPC64. Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com&gt; --- src/qemu/qemu_domain.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 6262bfe..963ff35 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -2599,7 +2599,11 @@ qemuDomainDefFormatBuf(virQEMUDriverPtr driver, usb = def->controllers[i]; } } - if (usb && usb->idx == 0 && usb->model == -1) { + /* The original purpose of the check was the migration compatibility + * with libvirt <= 0.9.4. Limitation doesn't apply to other archs + * and can cause problems on PPC64. + */ + if (ARCH_IS_X86(def->os.arch) && usb && usb->idx == 0 && usb->model == -1) { VIR_DEBUG("Removing default USB controller from domain '%s'" " for migration compatibility", def->name); toremove++;