Bodo reported that on the Asrock M3A UCC, v3.12.6 hangs during boot unless
he uses "pci=nocrs". This regression was caused by 7bc5e3f2be ("x86/PCI:
use host bridge _CRS info by default on 2008 and newer machines"), which
appeared in v2.6.34.
The reason is that the HPET address appears in a PCI device BAR, and this
address is not contained in any of the host bridge windows. Linux moves
the PCI BAR into a window, but the original address was published via the
HPET table and an ACPI device, so changing the BAR is a bad idea. Here's
the dmesg info:
ACPI: HPET id: 0x43538301 base: 0xfed00000
pci_root PNP0A03:00: host bridge window [mem 0xd0000000-0xdfffffff]
pci_root PNP0A03:00: host bridge window [mem 0xf0000000-0xfebfffff]
pci 0000:00:14.0: [1002:4385] type 0 class 0x000c05
pci 0000:00:14.0: reg 14: [mem 0xfed00000-0xfed003ff]
hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
pnp 00:06: Plug and Play ACPI device, IDs PNP0103 (active)
pnp 00:06: [mem 0xfed00000-0xfed003ff]
When we notice the BAR is not in a host bridge window, we try to move it,
but that causes a hang shortly thereafter:
pci 0000:00:14.0: no compatible bridge window for [mem 0xfed00000-0xfed003ff]
pci 0000:00:14.0: BAR 1: assigned [mem 0xf0000000-0xf00003ff]
This patch marks the BAR as IORESOURCE_PCI_FIXED to prevent Linux from
moving it. This depends on a previous patch ("x86/PCI: Don't try to move
IORESOURCE_PCI_FIXED resources") to check for this flag when
pci_claim_resource() fails.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=68591
Reported-and-tested-by: Bodo Eggert <7eggert@gmx.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
44c8bdbe32