[PATCH] kvmtool: don't use PCI config space IRQ line field

On Fri, Feb 06, 2015 at 07:02:25PM +0000, Peter Maydell wrote:

On 6 February 2015 at 18:55, Will Deacon [off-list ref] wrote:

quoted

On Wed, Feb 04, 2015 at 03:39:50PM +0000, Andre Przywara wrote:

quoted

In PCI config space there is an interrupt line field (offset 0x3f),
which is used to initially communicate the IRQ line number from
firmware to the OS. _Hardware_ should never use this information,
as the OS is free to write any information in there.

Is this true even with probe-only? I appreciate that this isn't a BAR,
but it still feels odd for Linux to write this in that case.

The hardware (model) shouldn't be doing anything with the value
in this register anyway, so I think this change to kvmtool is
correct regardless of Linux's behaviour.

Well, kvmtool is also pretending to be firmware in this case, which is why
it passes things like probe-only and PSCI nodes.

Will