On Mon, 15 Apr 2013 10:45:24 -0300 Eduardo Habkost <ehabk...@redhat.com> wrote:
> On Mon, Apr 15, 2013 at 03:37:00PM +0200, Igor Mammedov wrote: > [...] > > > > > ID to be directly specified in the device_add/-device options. > > > > > That's how real CPUs work: as the CPU manufacturer doesn't know > > > > > what will be the package ID of the CPU, the APIC IDs are not > > > > > hardcoded in the CPU; they are calculated based on the CPU topology > > > > > and some socket identifier signal coming from the board. > > > > that is why apic_id has been made a property, to be set from outside. > > > > > > True. I believe the conflict here is: we want other objects to set the > > > APIC ID (be it the board, or socket/core objects), but at the same time > > > it would be interesting to not expose the APIC ID outside QEMU. Being > > > too flexible regarding the APIC ID is more likely to cause problems > > > later. > > > > > > That said, I don't mind having a "apic-id" property because it is easier > > > to simply expose it directly. But do you agree that: 1) we don't really > > > need to expose it to be set from outside QEMU; 2) we shouldn't require > > > it to be set from outside QEMU; 3) we should recommend users to not try > > > to fiddle it with? > > Due to nature of per thread CPU hotplug, management will have to specify > > some kind of ID to specify which CPU is being plugged. Management really > > doesn't/shouldn't care what this ID is. > > As long as management really doesn't/shouldn't care what the ID is, > exposing the APIC ID in the form of an opaque CPU identifier wouldn't be > a problem to me. I just wanted to make clarify if we agree that messing > with the APIC ID directly won't be recommended and that the "apic-id" > property will be for QEMU internal use only. On contrary, it's useful external feature, x86 guests see only APIC ID, since it's the only ID they [should] know about. So guest aware mgmt could definitely use apic_id propery to correlate CPU in guest with QEMU view of them.
