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Commit 0637a70a authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen
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[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: default avatarAndi Kleen <ak@suse.de>
parent 8f60774a

Documentation/kernel-parameters.txt

+5 −1
Original line number Diff line number Diff line
@@ -1240,7 +1240,11 @@ running once the system is up. 
				bootloader. This is currently used on

				IXP2000 systems where the bus has to be

				configured a certain way for adjunct CPUs.



		noearly		[X86] Don't do any early type 1 scanning.

				This might help on some broken boards which

				machine check when some devices' config space

				is read. But various workarounds are disabled

				and some IOMMU drivers will not work.

	pcmv=		[HW,PCMCIA] BadgePAD 4



	pd.		[PARIDE]

arch/i386/kernel/acpi/earlyquirk.c

+5 −1
Original line number Diff line number Diff line
@@ -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++) {

arch/i386/pci/common.c

+4 −0
Original line number Diff line number Diff line
@@ -242,6 +242,10 @@ char * __devinit pcibios_setup(char *str) 
		acpi_noirq_set();

		return NULL;

	}

	else if (!strcmp(str, "noearly")) {

		pci_probe |= PCI_PROBE_NOEARLY;

		return NULL;

	}

#ifndef CONFIG_X86_VISWS

	else if (!strcmp(str, "usepirqmask")) {

		pci_probe |= PCI_USE_PIRQ_MASK;

arch/i386/pci/early.c

+8 −0
Original line number Diff line number Diff line 
#include <linux/kernel.h>

#include <linux/pci.h>

#include <asm/pci-direct.h>

#include <asm/io.h>

#include "pci.h"



/* Direct PCI access. This is used for PCI accesses in early boot before

   the PCI subsystem works. */
@@ -42,3 +44,9 @@ void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset, 
	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);

	outl(val, 0xcfc);

}



int early_pci_allowed(void)

{

	return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==

			PCI_PROBE_CONF1;

}

arch/i386/pci/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#define PCI_PROBE_CONF2		0x0004

#define PCI_PROBE_MMCONF	0x0008

#define PCI_PROBE_MASK		0x000f

#define PCI_PROBE_NOEARLY	0x0010



#define PCI_NO_SORT		0x0100

#define PCI_BIOS_SORT		0x0200