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Date: Thu, 21 Oct 2010 15:23:39 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/bios changes for v2.6.37
Linus,
Please pull the latest x86-bios-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-bios-for-linus
Thanks,
Ingo
------------------>
H. Peter Anvin (2):
x86, bios: By default, reserve the low 64K for all BIOSes
x86, bios: Make the x86 early memory reservation a kernel option
Documentation/kernel-parameters.txt | 5 ++
arch/x86/Kconfig | 47 +++++++++------
arch/x86/kernel/setup.c | 106 ++++++++++-------------------------
3 files changed, 63 insertions(+), 95 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2c85c06..41ce93e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2150,6 +2150,11 @@ and is between 256 and 4096 characters. It is defined in the file
Reserves a hole at the top of the kernel virtual
address space.
+ reservelow= [X86]
+ Format: nn[K]
+ Set the amount of memory to reserve for BIOS at
+ the bottom of the address space.
+
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cea0cd9..d359000 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1326,25 +1326,34 @@ config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
Set whether the default state of memory_corruption_check is
on or off.
-config X86_RESERVE_LOW_64K
- bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
- default y
- ---help---
- Reserve the first 64K of physical RAM on BIOSes that are known
- to potentially corrupt that memory range. A numbers of BIOSes are
- known to utilize this area during suspend/resume, so it must not
- be used by the kernel.
-
- Set this to N if you are absolutely sure that you trust the BIOS
- to get all its memory reservations and usages right.
-
- If you have doubts about the BIOS (e.g. suspend/resume does not
- work or there's kernel crashes after certain hardware hotplug
- events) and it's not AMI or Phoenix, then you might want to enable
- X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
- corruption patterns.
-
- Say Y if unsure.
+config X86_RESERVE_LOW
+ int "Amount of low memory, in kilobytes, to reserve for the BIOS"
+ default 64
+ range 4 640
+ ---help---
+ Specify the amount of low memory to reserve for the BIOS.
+
+ The first page contains BIOS data structures that the kernel
+ must not use, so that page must always be reserved.
+
+ By default we reserve the first 64K of physical RAM, as a
+ number of BIOSes are known to corrupt that memory range
+ during events such as suspend/resume or monitor cable
+ insertion, so it must not be used by the kernel.
+
+ You can set this to 4 if you are absolutely sure that you
+ trust the BIOS to get all its memory reservations and usages
+ right. If you know your BIOS have problems beyond the
+ default 64K area, you can set this to 640 to avoid using the
+ entire low memory range.
+
+ If you have doubts about the BIOS (e.g. suspend/resume does
+ not work or there's kernel crashes after certain hardware
+ hotplug events) then you might want to enable
+ X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
+ typical corruption patterns.
+
+ Leave this to the default value of 64 if you are unsure.
config MATH_EMULATION
bool
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c3a4fbb..af277e3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -618,79 +618,7 @@ static __init void reserve_ibft_region(void)
reserve_early_overlap_ok(addr, addr + size, "ibft");
}
-#ifdef CONFIG_X86_RESERVE_LOW_64K
-static int __init dmi_low_memory_corruption(const struct dmi_system_id *d)
-{
- printk(KERN_NOTICE
- "%s detected: BIOS may corrupt low RAM, working around it.\n",
- d->ident);
-
- e820_update_range(0, 0x10000, E820_RAM, E820_RESERVED);
- sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
-
- return 0;
-}
-#endif
-
-/* List of systems that have known low memory corruption BIOS problems */
-static struct dmi_system_id __initdata bad_bios_dmi_table[] = {
-#ifdef CONFIG_X86_RESERVE_LOW_64K
- {
- .callback = dmi_low_memory_corruption,
- .ident = "AMI BIOS",
- .matches = {
- DMI_MATCH(DMI_BIOS_VENDOR, "American Megatrends Inc."),
- },
- },
- {
- .callback = dmi_low_memory_corruption,
- .ident = "Phoenix BIOS",
- .matches = {
- DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies"),
- },
- },
- {
- .callback = dmi_low_memory_corruption,
- .ident = "Phoenix/MSC BIOS",
- .matches = {
- DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix/MSC"),
- },
- },
- /*
- * AMI BIOS with low memory corruption was found on Intel DG45ID and
- * DG45FC boards.
- * It has a different DMI_BIOS_VENDOR = "Intel Corp.", for now we will
- * match only DMI_BOARD_NAME and see if there is more bad products
- * with this vendor.
- */
- {
- .callback = dmi_low_memory_corruption,
- .ident = "AMI BIOS",
- .matches = {
- DMI_MATCH(DMI_BOARD_NAME, "DG45ID"),
- },
- },
- {
- .callback = dmi_low_memory_corruption,
- .ident = "AMI BIOS",
- .matches = {
- DMI_MATCH(DMI_BOARD_NAME, "DG45FC"),
- },
- },
- /*
- * The Dell Inspiron Mini 1012 has DMI_BIOS_VENDOR = "Dell Inc.", so
- * match on the product name.
- */
- {
- .callback = dmi_low_memory_corruption,
- .ident = "Phoenix BIOS",
- .matches = {
- DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 1012"),
- },
- },
-#endif
- {}
-};
+static unsigned reserve_low = CONFIG_X86_RESERVE_LOW << 10;
static void __init trim_bios_range(void)
{
@@ -698,8 +626,14 @@ static void __init trim_bios_range(void)
* A special case is the first 4Kb of memory;
* This is a BIOS owned area, not kernel ram, but generally
* not listed as such in the E820 table.
+ *
+ * This typically reserves additional memory (64KiB by default)
+ * since some BIOSes are known to corrupt low memory. See the
+ * Kconfig help text for X86_RESERVE_LOW.
*/
- e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);
+ e820_update_range(0, ALIGN(reserve_low, PAGE_SIZE),
+ E820_RAM, E820_RESERVED);
+
/*
* special case: Some BIOSen report the PC BIOS
* area (640->1Mb) as ram even though it is not.
@@ -709,6 +643,28 @@ static void __init trim_bios_range(void)
sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
}
+static int __init parse_reservelow(char *p)
+{
+ unsigned long long size;
+
+ if (!p)
+ return -EINVAL;
+
+ size = memparse(p, &p);
+
+ if (size < 4096)
+ size = 4096;
+
+ if (size > 640*1024)
+ size = 640*1024;
+
+ reserve_low = size;
+
+ return 0;
+}
+
+early_param("reservelow", parse_reservelow);
+
/*
* Determine if we were loaded by an EFI loader. If so, then we have also been
* passed the efi memmap, systab, etc., so we should use these data structures
@@ -863,8 +819,6 @@ void __init setup_arch(char **cmdline_p)
dmi_scan_machine();
- dmi_check_system(bad_bios_dmi_table);
-
/*
* VMware detection requires dmi to be available, so this
* needs to be done after dmi_scan_machine, for the BP.
--
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