Bjorn Helgaas wrote: > On Sunday 04 October 2009 10:54:24 pm Yinghai Lu wrote: >> for intel system with multi IOH. we could read peer root resource from PCI conf, >> and don't trust _CRS again for root bus > > Ugh. Are we going to end up with amd_bus.c, intel_bus.c, nvidia_bus.c, > broadcom_bus.c, serverworks_bus.c, etc.? only needed when you have muti ... > > This is basically a simple PCI host bridge driver, but it's completely > separate from the ACPI pci_root.c driver, and it completely ignores > useful things like multiple domain (_SEG) support and address translation > (_TRA) support. These are going to be important issues for large x86 > machines. > > I think this is leading toward an architectural mess. Yes, we have > issues with _CRS for root bridges. But ACPI does give us a generic > framework powerful enough to handle everything you're doing here. In > my opinion, we should fix the implementation issues with that framework > rather than adding platform-specific setup code every time we trip > over something. again we should trust HW conf than BIOS. > > I expect that will mean some quirks in pci_root.c, and maybe even some > code similar to pci_root_bus_res() to validate or override what we learn > from _CRS. But we ought to try for some conceptual integrity in the > design by putting all the putting all the host bridge driver code together. > > What is the specific problem solved by this patch? Does "pci=use_crs" > address any of that problem? (I know "pci=use_crs" breaks some machines, > and I know it's unacceptable to require users to use it. But I want to > understand whether the concept is related, and whether you've tripped > over a BIOS defect or a Linux pci_root.c defect.) BIOS doesn't allocate resource to some pci devices when too many devices. and need kernel to allocate resource ( 32bit mmio, 64 mmio) to those devices. current only known fw that can allocate mmio 64 ( with correct setting) is LinuxBIOS. also could help os to fend off some range that is wrongly allocated by BIOS that is cross the boundary between different peer root bus. _CRS doesn't report any MMIO 64 range, even HW does have that set. YH -- 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
