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

* '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

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ed05a4a..a2ffd6b 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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.
 

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a1bd569..b867649 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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
-       ---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 df770ad..6154701 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -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.