[PATCH] x86: Allow disabling early pci scans with pci=noearly or disallowing conf1

Some buggy systems can machine check when config space accesses
happen for some non existent devices.  i386/x86-64 do some early
device scans that might trigger this. Allow pci=noearly to disable
this. Also when type 1 is disabling also don't do any early
accesses which are always type1.

This moves the pci= configuration parsing to be a early parameter.
I don't think this can break anything because it only changes
a single global that is only used by PCI.

Cc: gregkh@suse.de
Cc: Trammell Hudson <hudson@osresearch.net>

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/i386/kernel/acpi/earlyquirk.c b/arch/i386/kernel/acpi/earlyquirk.c
index 1649a175a206..fe799b11ac0a 100644
--- a/arch/i386/kernel/acpi/earlyquirk.c
+++ b/arch/i386/kernel/acpi/earlyquirk.c
@@ -48,7 +48,11 @@ void __init check_acpi_pci(void)
         int num, slot, func;
 
         /* Assume the machine supports type 1. If not it will 
-           always read ffffffff and should not have any side effect. */
+           always read ffffffff and should not have any side effect.
+           Actually a few buggy systems can machine check. Allow the user
+           to disable it by command line option at least -AK */
+        if (!early_pci_allowed())
+                return;
 
         /* Poor man's PCI discovery */
         for (num = 0; num < 32; num++) {