On 04/10/2014 11:26 PM, Alexander Graf wrote: > > On 10.04.14 15:24, Alexey Kardashevskiy wrote: >> On 04/10/2014 10:51 PM, Alexander Graf wrote: >>> On 14.03.14 05:18, Alexey Kardashevskiy wrote: >>>> The current allocator returns IRQ numbers from a pool and does not >>>> support IRQs reuse in any form as it did not keep track of what it >>>> previously returned, it only had the last returned IRQ. >>>> However migration may change interrupts for devices depending on >>>> their order in the command line. >>> Wtf? Nonono, this sounds very bogus and wrong. Migration shouldn't change >>> anything. >> >> I put wrong commit message. By change I meant that the default state before >> the destination guest started accepting migration is different from what >> the destination guest became after migration finished. And migration cannot >> avoid changing this default state. > > Ok, why is the IRQ configuration different?
Because QEMU creates devices in the order as in the command line, and libvirt changes this order - the XML used to create the guest and the XML which is sends during migration are different. libvirt thinks it is ok while it keeps @reg property for (for example) spapr-vscsi devices but it is not because since the order is different, devices call IRQ allocator in different order and get different IRQs. -- Alexey
