[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>

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++) {