On Fri, Jan 15, 2016 at 12:19:38PM -0600, Bjorn Helgaas wrote: > I also have a more substantive question about the flags setup. I > think you should not clear IORESOURCE_MEM_64. The intent of > IORESOURCE_MEM_64 is to describe the *capability* of a BAR, not its > contents. But I assume you cleared it for a reason. vmd->resources[n] > are not BARs, so the PCI core won't assign resources to them like it > does for BAR, so we shouldn't care about IORESOURCE_MEM_64 for that > reason. Is there some other reason IORESOURCE_MEM_64 makes a > difference there? Hi Bjorn & Keith: I did this to fix an issue in pre-RFC code. The flag is subtly restrictive in one specific scenario: spec-compliant PCIe ports lack the ability to specify a 64-bit, non-prefetchable range. IORESOURCE_MEM_64 directs the PCI subsystem to put the address into the 64-bit *prefetchable* range. Below the port, the "prefetchable" propoerty *is* restrictive: the addresses can't be used for non-prefetchable BARs. Thus, in the specific case where a 64-bit non-prefetchable VMD bar happens to contain a 32-bit address, removing the IORESOURCE_MEM_64 flag allows the address resource to be used for *any* non-prefetchable BARs (32-bit or 64-bit) downstream. -- 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
