On Sun, 2014-11-23 at 21:20 +0100, Thomas Gleixner wrote: > On Fri, 21 Nov 2014, Alex Williamson wrote: > > For the most part multivector MSI is not supported and drivers and > > hardware wanting multiple vectors opt for MSI-X instead. It seems > > though that having the ability to query the arch/platform code to > > determine whether allocating multiple MSI vectors will ever succeed > > is a useful thing. For instance, vfio-pci can use this to determine > > whether to expose multiple MSI vectors to the user. If we know we > > cannot ever support more than one vector, we have a better shot at > > the userspace driver working, especially if it's a guest OS, if we > > only expose one vector as being available in the interface. > > > > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > --- > > > > drivers/pci/msi.c | 5 +++++ > > include/linux/msi.h | 1 + > > 2 files changed, 6 insertions(+) > > > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > > index 9fab30a..36b503a 100644 > > --- a/drivers/pci/msi.c > > +++ b/drivers/pci/msi.c > > @@ -79,6 +79,11 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type) > > return 0; > > } > > > > +bool __weak arch_supports_multivector_msi(struct pci_dev *dev) > > Please not another weak arch function. We are in the process to reduce > them not to extend them. > > arch_supports is pretty much wrong here anyway. We are moving away > from arch MSI dependencies simply because it's not a arch property per > se. > > Multi MSI is a property of the underlying interrupt controllers and > there might be several MSI interrupt domains on a given system. They > can or cannot support multi MSI. > > The current x86 implementation is a tangled maze and Jiang is in the > process to distangle it completely. Until thats done x86 is not going > to add new ad hoc interfaces. > > Once we converted everything over to the new hierarchical irqdomains > we can add such an interface to the code, but for now I'm not > accepting anything like that into x86 msi related code. Ok, I guess I can do some ugliness with associating the IOMMU IRQ remapping capability with multivector MSI support within an #ifdef x86 block. Gross, but I think that's as accurate as I can get w/o a hook through the MSI code. Is there any target for the refactoring you mention? Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
