This patch introduces a user for the e820_all_mapped function:
There have been several machines that don't have a working MMCONFIG, often
because of a buggy MCFG table in the ACPI bios. This patch adds a simple
sanity check that detects a whole bunch of these cases, and when it detects
it, linux now boots rather than crash-and-burns. The accuracy of this
detection can in principle be improved if there was a "is this entire range
in e820 with THIS attribute", but no such function exist and the complexity
needed for this is not really worth it; this simple check already catches
most cases anyway.
Signed-off-by: Arjan van de Ven <[email protected]>
---
arch/x86_64/pci/mmconfig.c | 10 ++++++++++
1 file changed, 10 insertions(+)
Index: linux-2.6.16-mmconfig/arch/x86_64/pci/mmconfig.c
===================================================================
--- linux-2.6.16-mmconfig.orig/arch/x86_64/pci/mmconfig.c
+++ linux-2.6.16-mmconfig/arch/x86_64/pci/mmconfig.c
@@ -9,6 +9,8 @@
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/bitmap.h>
+#include <asm/e820.h>
+
#include "pci.h"
#define MMCONFIG_APER_SIZE (256*1024*1024)
@@ -161,6 +163,14 @@ void __init pci_mmcfg_init(void)
(pci_mmcfg_config[0].base_address == 0))
return;
+ if (!e820_all_mapped(pci_mmcfg_config[0].base_address,
+ pci_mmcfg_config[0].base_address + MMCONFIG_APER_SIZE,
+ E820_RESERVED)) {
+ printk(KERN_INFO "PCI: BIOS Bug: MCFG area is not E820-reserved\n");
+ printk(KERN_INFO "PCI: Not using MMCONFIG.\n");
+ return;
+ }
+
/* RED-PEN i386 doesn't do _nocache right now */
pci_mmcfg_virt = kmalloc(sizeof(*pci_mmcfg_virt) * pci_mmcfg_config_num, GFP_KERNEL);
if (pci_mmcfg_virt == NULL) {
-
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