Commit-ID: 9ea77bdb39b62c9bf9fd3cdd1c25a9420bccd380
Gitweb: http://git.kernel.org/tip/9ea77bdb39b62c9bf9fd3cdd1c25a9420bccd380
Author: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 25 Aug 2010 16:38:20 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Wed, 25 Aug 2010 17:10:49 -0700
x86, bios: Make the x86 early memory reservation a kernel option
Add a kernel command-line option so the x86 early memory reservation
size can be adjusted at runtime instead of only at compile time.
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
LKML-Reference: <tip-d0cd7425fab774a480cce17c2f649984312d0b55@xxxxxxxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 5 +++++
arch/x86/Kconfig | 2 +-
arch/x86/kernel/setup.c | 28 ++++++++++++++++++++++++++--
3 files changed, 32 insertions(+), 3 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 683ae8f..d359000 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1326,7 +1326,7 @@ config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
Set whether the default state of memory_corruption_check is
on or off.
-config X86_LOW_RESERVE
+config X86_RESERVE_LOW
int "Amount of low memory, in kilobytes, to reserve for the BIOS"
default 64
range 4 640
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index eb87f1c..af277e3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -618,6 +618,8 @@ static __init void reserve_ibft_region(void)
reserve_early_overlap_ok(addr, addr + size, "ibft");
}
+static unsigned reserve_low = CONFIG_X86_RESERVE_LOW << 10;
+
static void __init trim_bios_range(void)
{
/*
@@ -627,9 +629,9 @@ static void __init trim_bios_range(void)
*
* This typically reserves additional memory (64KiB by default)
* since some BIOSes are known to corrupt low memory. See the
- * Kconfig help text for X86_LOW_RESERVE.
+ * Kconfig help text for X86_RESERVE_LOW.
*/
- e820_update_range(0, ALIGN(CONFIG_X86_LOW_RESERVE << 10, PAGE_SIZE),
+ e820_update_range(0, ALIGN(reserve_low, PAGE_SIZE),
E820_RAM, E820_RESERVED);
/*
@@ -641,6 +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
--
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