On Tue, Feb 18, 2014 at 08:15:12PM +0000, Arnd Bergmann wrote: > On Tuesday 18 February 2014 18:44:20 Will Deacon wrote: > > On Tue, Feb 18, 2014 at 06:21:42PM +0000, Jason Gunthorpe wrote: > > > On Tue, Feb 18, 2014 at 12:20:43PM +0000, Will Deacon wrote: > > > > + > > > > + // BUS_ADDRESS(3) CPU_PHYSICAL(2) SIZE(2) > > > > + ranges = <0x1000000 0x0 0x00000000 0x0 0x00000000 0x0 0x00010000>, > > > ^^^^^^^^^^^^^^ > > > > > > This probably shouldn't be 0 in the example, nor in your kvm tool > > > output. For example purposes any value will do. > > > > Hmm, so kvmtool actually provides a PC ioport at 0x0, which is handy since > > there's an 8250 down there. That means we have: > > > > 0x0 - 0x6200 : Weird PC stuff > > 0x6200 - 0x10000 : PCI IO space > > > > Should I just change everything to be offset by 0x6200? > > Some more comments about this: > > * After I looked at the kvmtool code some more, I think it would be nice to > actually move the I/O space window to a nonzero location, e.g. between the > PCI space and the AXI space. It's really confusing the way it is, and easy > to introduce bugs if you have any code that accidentally relies on the > numbers matching up. For all I can tell, kvmtool should just work fine > with any definition of ARM_IOPORT_AREA, as long as you apply the trivial > patch below. Well, I think we need a bit more than that otherwise our I/O BARs won't be initialised correctly. > * pci_get_io_space_block() is a very confusing name for a function that > allocates a memory space block in kvmtool. It seems that KVM_IOPORT_AREA > is a misnomer for the same reason. Note that PowerPC sets KVM_IOPORT_AREA > to zero, but has the I/O space window at SPAPR_PCI_IO_WIN_ADDR, > which is non-zero. Agreed about pci_get_io_space_block being a misnomer, that's probably due some cleanup. I don't think KVM_IOPORT_AREA is too bad though (it's zero for PowerPC because I added it and don't have a platform to test on). > * It's interesting that you also support I/O space access to the PCI config > space through PC-Style ports 0cf8-0cff. Not sure if that helps at all, > but it is another standard way to probe the bus that could easily be > implemented as an alternative to CAM and ECAM, in a generic PCI host > driver. I won't add that initially, but if somebody needs it then it's easy to extend what we currently have. Will -- 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
