Added cc: stable@xxxxxxxxxx See: https://patchwork.kernel.org/patch/189182/ https://patchwork.kernel.org/patch/189232/ https://patchwork.kernel.org/patch/189242/ https://patchwork.kernel.org/patch/189252/ On Friday, September 17, 2010 04:32:06 pm Bjorn Helgaas wrote: > When we move PCI devices, we currently allocate space bottom-up, i.e., we look > at PCI bus resources in the order we found them, we look at gaps between child > resources bottom-up, and we align the new space at the bottom of an available > region. > > On x86, we move PCI devices more than we used to because we now pay attention > to the PCI host bridge windows from ACPI. For example, when we find a device > that's outside all the known host bridge windows, we try to move it into a > window, and we look for space starting at the bottom. > > Windows does similar device moves, but it looks for space top-down rather than > bottom-up. Since most machines are better-tested with Windows than Linux, this > difference means that Linux is more likely to trip over BIOS bugs in the PCI > host bridge window descriptions than Windows is. > > We've had several reports of Dell machines where the BIOS leaves the AHCI > controller outside the host bridge windows (BIOS bug #1), *and* the lowest > host bridge window includes an area that doesn't actually reach PCI (BIOS > bug #2). The result is that Windows (which moves AHCI to the top of a window) > works fine, while Linux (which moves AHCI to the bottom, buggy, area) doesn't > work. > > These patches change Linux to allocate space more like Windows does: > > 1) The x86 pcibios_align_resource() will choose space from the > end of an available area, not the beginning. > > 2) In the generic allocate_resource() path, we'll look for space > between existing children from the top, not from the bottom. > > 3) When pci_bus_alloc_resource() looks for available space, it > will start from the highest window, not the first one we found. > > This series fixes a 2.6.34 regression that prevents many Dell Precision > workstations from booting: > > https://bugzilla.kernel.org/show_bug.cgi?id=16228 > > Changes from v1 to v2: > - Moved check for allocating before the available area from > pcibios_align_resource() to find_resource(). Better to do it > after the alignment callback is done, and make it generic. > - Fixed pcibios_align_resource() alignment. If we start from the > end of the available area, we must align *downward*, not upward. > - Fixed pcibios_align_resource() ISA alias avoidance. Again, since > the starting point is the end of the area, we must align downward > when we avoid aliased areas. > > --- > > Bjorn Helgaas (4): > resources: ensure alignment callback doesn't allocate below available start > x86/PCI: allocate space from the end of a region, not the beginning > resources: allocate space within a region from the top down > PCI: allocate bus resources from the top down > > > arch/x86/pci/i386.c | 18 ++++++++++++----- > drivers/pci/bus.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++----- > kernel/resource.c | 50 +++++++++++++++++++++++++++++++----------------- > 3 files changed, 92 insertions(+), 29 deletions(-) > -- 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
