diff options
| -rw-r--r-- | sys/arch/amd64/pci/pci_machdep.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/sys/arch/amd64/pci/pci_machdep.c b/sys/arch/amd64/pci/pci_machdep.c index 66f5d2f3a96..0bf936461f2 100644 --- a/sys/arch/amd64/pci/pci_machdep.c +++ b/sys/arch/amd64/pci/pci_machdep.c @@ -1,4 +1,4 @@ -/* $OpenBSD: pci_machdep.c,v 1.45 2011/05/29 10:47:42 kettenis Exp $ */ +/* $OpenBSD: pci_machdep.c,v 1.46 2011/05/30 19:27:40 kettenis Exp $ */ /* $NetBSD: pci_machdep.c,v 1.3 2003/05/07 21:33:58 fvdl Exp $ */ /*- @@ -151,6 +151,49 @@ void pci_attach_hook(struct device *parent, struct device *self, struct pcibus_attach_args *pba) { + pci_chipset_tag_t pc = pba->pba_pc; + pcitag_t tag; + pcireg_t id, class; + + if (pba->pba_bus != 0) + return; + + /* + * In order to decide whether the system supports MSI we look + * at the host bridge, which should be device 0 function 0 on + * bus 0. It is better to not enable MSI on systems that + * support it than the other way around, so be conservative + * here. So we don't enable MSI if we don't find a host + * bridge there. We also deliberately don't enable MSI on + * chipsets from low-end manifacturers like VIA and SiS. + */ + tag = pci_make_tag(pc, 0, 0, 0); + id = pci_conf_read(pc, tag, PCI_ID_REG); + class = pci_conf_read(pc, tag, PCI_CLASS_REG); + + if (PCI_CLASS(class) != PCI_CLASS_BRIDGE || + PCI_SUBCLASS(class) != PCI_SUBCLASS_BRIDGE_HOST) + return; + + switch (PCI_VENDOR(id)) { + case PCI_VENDOR_INTEL: + case PCI_VENDOR_NVIDIA: + case PCI_VENDOR_AMD: + pba->pba_flags |= PCI_FLAGS_MSI_ENABLED; + break; + } + + /* + * Don't enable MSI on a HyperTransport bus. In order to + * determine that bus 0 is a HyperTransport bus, we look at + * device 24 function 0, which is the HyperTransport + * host/primary interface integrated on most 64-bit AMD CPUs. + * If that device has a HyperTransport capability, bus 0 must + * be a HyperTransport bus and we disable MSI. + */ + tag = pci_make_tag(pc, 0, 24, 0); + if (pci_get_capability(pc, tag, PCI_CAP_HT, NULL, NULL)) + pba->pba_flags &= ~PCI_FLAGS_MSI_ENABLED; } int |