Detect a certain type of PCIBIOS brain damage. For some reason,

some bios vendors took it apon themselves to "censor" the
host->pci bridges from PCIBIOS callers, even when the caller
explicitly asks for them.  This includes certain Compaq machines
(eg: DL360) and some laptops.

If we detect this, shut down pcibios and revert to using IO
port bashing.

Under -current, apcica does a better job anyway.

2 files changed, 31 insertions, 0 deletions

diff --git a/sys/amd64/pci/pci_bus.c b/sys/amd64/pci/pci_bus.c
index dfd4967..b01cc2d 100644
--- a/sys/amd64/pci/pci_bus.c
+++ b/sys/amd64/pci/pci_bus.c
@@ -268,6 +268,7 @@ nexus_pcib_identify(driver_t *driver, device_t parent)
 	int pcifunchigh;
 	int found824xx = 0;
 	int found_orion = 0;
+	int found_pcibios_flaming_death = 0;
 	device_t child;
 	devclass_t pci_devclass;
 
@@ -359,6 +360,23 @@ nexus_pcib_identify(driver_t *driver, device_t parent)
 	}
 
 	/*
+	 * This is just freaking brilliant!  Some BIOS writers have
+	 * decided that we must be forcibly prevented from using
+	 * PCIBIOS to query the host->pci bridges.  If you try and
+	 * access configuration registers, it pretends there is
+	 * no pci device at that bus:device:function address.
+	 */
+	if (!found && pci_pcibios_active() && !found_pcibios_flaming_death) {
+		/* retry with the old mechanism, or fail */
+		if (pci_kill_pcibios() == 0)
+			return;
+		printf("nexus_pcib_identify: found broken PCIBIOS - disabling it and retrying.\n");
+		printf("nexus_pcib_identify: it is bogusly censoring host->pci bridges.\n");
+		found_pcibios_flaming_death = 1;
+		goto retry;
+	}
+
+	/*
 	 * Make sure we add at least one bridge since some old
 	 * hardware doesn't actually have a host-pci bridge device.
 	 * Note that pci_cfgregopen() thinks we have PCI devices..
diff --git a/sys/amd64/pci/pci_cfgreg.c b/sys/amd64/pci/pci_cfgreg.c
index 7b73486..3538969 100644
--- a/sys/amd64/pci/pci_cfgreg.c
+++ b/sys/amd64/pci/pci_cfgreg.c
@@ -71,6 +71,19 @@ static int	pcireg_cfgopen(void);
 static struct PIR_table	*pci_route_table;
 static int		pci_route_count;
 
+int
+pci_pcibios_active(void)
+{
+    return usebios;
+}
+
+int
+pci_kill_pcibios(void)
+{
+    usebios = 0;
+    return pcireg_cfgopen() != 0;
+}
+
 /* 
  * Initialise access to PCI configuration space 
  */