On Thu, 2006-03-23 at 20:02 +0100, Arjan van de Ven wrote:
> > That is e820_mapped(address, address+size, E820_RESERVED)
> >
> > And not having a size is definitely wrong on i386 too.
>
> s/wrong/not selective enough/
>
> and e820_mapped doesn't check this either anyway, at least not the way
> you imply it does.
>
> I'll do a new patch using this for x86_64 though, no need to make a
> second function like this.
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]>
diff -purN linux-2.6.16/arch/i386/kernel/setup.c linux-2.6.16-mmconfig/arch/i386/kernel/setup.c
--- linux-2.6.16/arch/i386/kernel/setup.c 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6.16-mmconfig/arch/i386/kernel/setup.c 2006-03-23 20:06:22.000000000 +0100
@@ -1377,6 +1377,27 @@ static void __init register_memory(void)
pci_mem_start, gapstart, gapsize);
}
+/*
+ * Check if an address is reserved in the e820 map
+ */
+int is_e820_reserved(u64 address)
+{
+ int i;
+ i = e820.nr_map;
+ while (--i >= 0) {
+ unsigned long long start = e820.map[i].addr;
+ unsigned long long end = start + e820.map[i].size;
+
+ if (address <=end && address >= start) {
+ if (e820.map[i].type == E820_RESERVED)
+ return 1;
+ else
+ return 0;
+ }
+ }
+ return 0;
+}
+
/* Use inline assembly to define this because the nops are defined
as inline assembly strings in the include files and we cannot
get them easily into strings. */
diff -purN linux-2.6.16/arch/i386/pci/mmconfig.c linux-2.6.16-mmconfig/arch/i386/pci/mmconfig.c
--- linux-2.6.16/arch/i386/pci/mmconfig.c 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6.16-mmconfig/arch/i386/pci/mmconfig.c 2006-03-23 20:06:22.000000000 +0100
@@ -12,6 +12,7 @@
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/acpi.h>
+#include <asm/e820.h>
#include "pci.h"
#define mmcfg_virt_addr ((void __iomem *) fix_to_virt(FIX_PCIE_MCFG))
@@ -183,6 +184,17 @@ static int __init pci_mmcfg_init(void)
(pci_mmcfg_config[0].base_address == 0))
goto out;
+ /*
+ * several bioses have a buggy MCFG table. While this is hard
+ * to test for conclusively, we know the value is defective
+ * if the memory isn't marked reserved in the e820 table
+ */
+ if (!is_e820_reserved(pci_mmcfg_config[0].base_address)) {
+ printk(KERN_INFO "PCI: BIOS Bug: MCFG area is not reserved\n");
+ printk(KERN_INFO "PCI: Not using MMCONFIG.\n");
+ goto out;
+ }
+
printk(KERN_INFO "PCI: Using MMCONFIG\n");
raw_pci_ops = &pci_mmcfg;
pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
diff -purN linux-2.6.16/arch/x86_64/kernel/e820.c linux-2.6.16-mmconfig/arch/x86_64/kernel/e820.c
--- linux-2.6.16/arch/x86_64/kernel/e820.c 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6.16-mmconfig/arch/x86_64/kernel/e820.c 2006-03-23 20:05:33.000000000 +0100
@@ -80,6 +80,11 @@ static inline int bad_addr(unsigned long
return 0;
}
+/*
+ * This function returns 1 if any part of the <start, end> range is in the
+ * E820 map having "type". There may be parts in this range that are not in
+ * E820 at all and/or parts with different types in addition.
+ */
int __init e820_mapped(unsigned long start, unsigned long end, unsigned type)
{
int i;
diff -purN linux-2.6.16/arch/x86_64/pci/mmconfig.c linux-2.6.16-mmconfig/arch/x86_64/pci/mmconfig.c
--- linux-2.6.16/arch/x86_64/pci/mmconfig.c 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6.16-mmconfig/arch/x86_64/pci/mmconfig.c 2006-03-23 20:08:21.000000000 +0100
@@ -9,6 +9,7 @@
#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 +162,19 @@ static int __init pci_mmcfg_init(void)
(pci_mmcfg_config[0].base_address == 0))
return 0;
+ /*
+ * several bioses have a buggy MCFG table. While this is hard
+ * to test for conclusively, we know the value is defective
+ * if the memory isn't marked reserved in the e820 table
+ */
+ if (!e820_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 reserved\n");
+ printk(KERN_INFO "PCI: Not using MMCONFIG.\n");
+ return 0;
+ }
+
/* 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) {
diff -purN linux-2.6.16/include/asm-i386/e820.h linux-2.6.16-mmconfig/include/asm-i386/e820.h
--- linux-2.6.16/include/asm-i386/e820.h 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6.16-mmconfig/include/asm-i386/e820.h 2006-03-23 20:06:22.000000000 +0100
@@ -35,6 +35,9 @@ struct e820map {
};
extern struct e820map e820;
+
+extern int is_e820_reserved(u64 address);
+
#endif/*!__ASSEMBLY__*/
#endif/*__E820_HEADER*/
-
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