On Mon, 2009-11-30 at 15:32 -0800, Yinghai Lu wrote: > Alex Williamson wrote: > > On Mon, 2009-11-30 at 14:12 -0800, Yinghai Lu wrote: > >> Alex Williamson wrote: > >>> I don't believe the PCI spec dictates whether the upper 32bit base > >>> should be 0 or -1, so it's purely a BIOS initialization choice and Linux > >>> should properly handle both. If the hardware only supports 32bit > >>> prefetchable windows, the hardware will drop the write, just as it did > >>> for every 2.6 kernel before 1f82de10. Thanks, > >> current code: > >> > >> #define PCI_PREF_RANGE_TYPE_MASK 0x0fUL > >> #define PCI_PREF_RANGE_TYPE_32 0x00 > >> #define PCI_PREF_RANGE_TYPE_64 0x01 > >> #define PCI_PREF_RANGE_MASK (~0x0fUL) > >> > >> if the HW state the pref mmio is 64bit, we will touch upper 32bit. otherwise we will not touch it. > > > > Really, where? Please paste the code that writes to > > PCI_PREF_BASE_UPPER32 in the case of hardware supporting a 64bit > > prefetchable window. I only see this happening if we are assigning it > > to an IORESOURCE_MEM_64 resources. > > IORESOURCE_MEM_64 get set when PCI_PREF_RANGE_TYPE_64 is set. > > in probe.c::pci_read_bridge_bases() Ah, I think I see where you're going. We only set IORESOURCE_MEM_64 if base <= limit, ie. the BIOS has programmed the prefetchable range. This is not a requirement by the PCI spec. In my case the BIOS has left base > limit, just as Linux would do if it disabled the range, so we never set this flag. > setup-bus.c::pci_bridge_check_ranges() This is only checking that the upper 32bits is actually implemented, should we have already set the IORESOURCE_MEM_64 from the function above, which we haven't. So, in my case I have a 64bit capable prefetchable range, that the BIOS has not programmed and is not required to program. We assign it to a 32bit window, and never touch the UPPER32 registers. 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
