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Merge branch 'x86-bios-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'x86-bios-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, bios: Make the x86 early memory reservation a kernel option
  x86, bios: By default, reserve the low 64K for all BIOSes
This commit is contained in:
Linus Torvalds 2010-10-21 13:06:49 -07:00
commit 781c5a67f1
3 changed files with 59 additions and 91 deletions
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5
Documentation/kernel-parameters.txt
View file

@ -2153,6 +2153,11 @@ 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.

39
arch/x86/Kconfig
View file

@ -1341,25 +1341,34 @@ 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
config X86_RESERVE_LOW
int "Amount of low memory, in kilobytes, to reserve for the BIOS"
default 64
range 4 640
---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.
Specify the amount of low memory to reserve for the BIOS.
Set this to N if you are absolutely sure that you trust the BIOS
to get all its memory reservations and usages right.
The first page contains BIOS data structures that the kernel
must not use, so that page must always be reserved.
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.
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.
Say Y if unsure.
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

106
arch/x86/kernel/setup.c
View file

@ -619,79 +619,7 @@ 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)
{
@ -699,8 +627,14 @@ 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.
@ -710,6 +644,28 @@ 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
@ -865,8 +821,6 @@ 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.