some BIOS only let AMD fam 10h handle bus0, and nvidia mcp55/ck804
to handle other buses. at that case MCFG will cover all over them.

but with acpi=off, we can not use MCFG. this patch will double check
the busnbits, and if it is less handling 256 bues, and acpi=off
will forcely reset the mmconf in msr, so we still use mmconf in above case.

Signed-off-by: Yinghai Lu <[EMAIL PROTECTED]>

Index: linux-2.6/arch/x86/kernel/setup_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup_64.c
+++ linux-2.6/arch/x86/kernel/setup_64.c
@@ -720,14 +720,21 @@ static void __cpuinit fam10h_check_enabl
 
        /* try to make sure that AP's setting is identical to BSP setting */
        if (val & FAM10H_MMIO_CONF_ENABLE) {
-               u64 base;
-               base = val & (0xffffULL << 32);
-               if (fam10h_pci_mmconf_base_status <= 0) {
-                       fam10h_pci_mmconf_base = base;
-                       fam10h_pci_mmconf_base_status = 1;
-                       return;
-               } else if (fam10h_pci_mmconf_base ==  base)
-                       return;
+               unsigned busnbits;
+               busnbits = (val >> FAM10H_MMIO_CONF_BUSRANGE_SHIFT) &
+                       FAM10H_MMIO_CONF_BUSRANGE_MASK;
+
+               /* only trust the one handle 256 buses, if acpi=off */
+               if (!acpi_pci_disabled || busnbits >= 8) {
+                       u64 base;
+                       base = val & (0xffffULL << 32);
+                       if (fam10h_pci_mmconf_base_status <= 0) {
+                               fam10h_pci_mmconf_base = base;
+                               fam10h_pci_mmconf_base_status = 1;
+                               return;
+                       } else if (fam10h_pci_mmconf_base ==  base)
+                               return;
+               }
        }
 
        /*
--
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