Re: [Qemu-devel] [PATCH V14 0/3] Virtual Machine Generation ID

[Michael S. Tsirkin]

On Tue, Mar 03, 2015 at 05:18:12PM +0100, Igor Mammedov wrote:
> Changes since v13:
>  * fix comment style to /*... */ in testcase
>  * make BAR TARGET_PAGE_SIZE as required by spec
>  * make BAR prefetchable, spec also says that it shouldn't be
>    marked as non cached
>  * ACPI part
>     * merge separate VGID device with PCI device description
>     * mark device as not shown in UI,
>       it hides "VM Generation ID" device from device manager
>       and leaves only "PCI Standard RAM Controller" device there

In an offline chat, Yan (Cc) mentioned that with windows guests,
PCI rebalancing can move BAR values around.
Yan, could you comment on-list please?
Is there a way to force this, for testing?

ACPI spec mentions this:
If a platform uses a PCI BAR Target operation region, an ACPI OS will
not load a native device driver for the associated PCI function. For
example, if any of the BARs in a PCI function are associated with a PCI
BAR Target operation region, then the OS will assume that the PCI
function is to be entirely under the control of the ACPI BIOS. No driver
will be loaded. Thus, a PCI function can be used as a platform
controller for some task (hot-plug PCI, and so on) that the ACPI BIOS
performs.

This might also avoid driver prompt from windows?

-- 
MST