From c898faf91b3ec6b0f6efa35831b3984fa3331db0 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 5 May 2009 17:28:56 -0400 Subject: x86: 46 bit physical address support on 64 bits Extend the maximum addressable memory on x86-64 from 2^44 to 2^46 bytes. This requires some shuffling around of the vmalloc and virtual memmap memory areas, to keep them away from the direct mapping of up to 64TB of physical memory. This patch also introduces a guard hole between the vmalloc area and the virtual memory map space. There's really no good reason why we wouldn't have a guard hole there. [ Impact: future hardware enablement ] Signed-off-by: Rik van Riel LKML-Reference: <20090505172856.6820db22@cuia.bos.redhat.com> Signed-off-by: H. Peter Anvin --- Documentation/x86/x86_64/mm.txt | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt index 29b52b14d0b..53941323584 100644 --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -6,10 +6,11 @@ Virtual memory map with 4 level page tables: 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole -ffff880000000000 - ffffc0ffffffffff (=57 TB) direct mapping of all phys. memory -ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole -ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space -ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB) +ffff880000000000 - ffffc8ffffffffff (=64 TB) direct mapping of all phys. memory +ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole +ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space +ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole +ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) ... unused hole ... ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space -- cgit v1.2.3 From 2feceeff1e771850e49f9074307f071964fd9e3e Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 5 May 2009 19:07:07 -0700 Subject: x86: fix typo in address space documentation Fix a trivial typo in Documentation/x86/x86_64/mm.txt. [ Impact: documentation only ] Signed-off-by: H. Peter Anvin Cc: Rik van Riel --- Documentation/x86/x86_64/mm.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt index 53941323584..d6498e3cd71 100644 --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -6,7 +6,7 @@ Virtual memory map with 4 level page tables: 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole -ffff880000000000 - ffffc8ffffffffff (=64 TB) direct mapping of all phys. memory +ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole -- cgit v1.2.3 From d297366ba692faf1f0384811a6ff0b20c3470b1b Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Mon, 11 May 2009 16:06:23 -0700 Subject: x86: document new bzImage fields Document the new bzImage fields for kernel memory placement. [ Impact: adds documentation ] Signed-off-by: H. Peter Anvin --- Documentation/x86/boot.txt | 69 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 4 deletions(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt index e0203662f9e..cf8dfc70a11 100644 --- a/Documentation/x86/boot.txt +++ b/Documentation/x86/boot.txt @@ -50,6 +50,11 @@ Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical pointer to single linked list of struct setup_data. +Protocol 2.10: (Kernel 2.6.31) A protocol for relaxed alignment + beyond the kernel_alignment added, new init_size and + pref_address fields. + + **** MEMORY LAYOUT The traditional memory map for the kernel loader, used for Image or @@ -173,7 +178,7 @@ Offset Proto Name Meaning 022C/4 2.03+ ramdisk_max Highest legal initrd address 0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel 0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not -0235/1 N/A pad2 Unused +0235/1 2.10+ min_alignment Minimum alignment, as a power of two 0236/2 N/A pad3 Unused 0238/4 2.06+ cmdline_size Maximum size of the kernel command line 023C/4 2.07+ hardware_subarch Hardware subarchitecture @@ -182,6 +187,8 @@ Offset Proto Name Meaning 024C/4 2.08+ payload_length Length of kernel payload 0250/8 2.09+ setup_data 64-bit physical pointer to linked list of struct setup_data +0258/8 2.10+ pref_address Preferred loading address +0260/4 2.10+ init_size Linear memory required during initialization (1) For backwards compatibility, if the setup_sects field contains 0, the real value is 4. @@ -482,11 +489,19 @@ Protocol: 2.03+ 0x37FFFFFF, you can start your ramdisk at 0x37FE0000.) Field name: kernel_alignment -Type: read (reloc) +Type: read/modify (reloc) Offset/size: 0x230/4 -Protocol: 2.05+ +Protocol: 2.05+ (read), 2.10+ (modify) + + Alignment unit required by the kernel (if relocatable_kernel is + true.) A relocatable kernel that is loaded at an alignment + incompatible with the value in this field will be realigned during + kernel initialization. - Alignment unit required by the kernel (if relocatable_kernel is true.) + Starting with protocol version 2.10, this reflects the kernel + alignment preferred for optimal performance; it is possible for the + loader to modify this field to permit a lesser alignment. See the + min_alignment and pref_address field below. Field name: relocatable_kernel Type: read (reloc) @@ -498,6 +513,22 @@ Protocol: 2.05+ After loading, the boot loader must set the code32_start field to point to the loaded code, or to a boot loader hook. +Field name: min_alignment +Type: read (reloc) +Offset/size: 0x235/1 +Protocol: 2.10+ + + This field, if nonzero, indicates as a power of two the minimum + alignment required, as opposed to preferred, by the kernel to boot. + If a boot loader makes use of this field, it should update the + kernel_alignment field with the alignment unit desired; typically: + + kernel_alignment = 1 << min_alignment + + There may be a considerable performance cost with an excessively + misaligned kernel. Therefore, a loader should typically try each + power-of-two alignment from kernel_alignment down to this alignment. + Field name: cmdline_size Type: read Offset/size: 0x238/4 @@ -582,6 +613,36 @@ Protocol: 2.09+ sure to consider the case where the linked list already contains entries. +Field name: pref_address +Type: read (reloc) +Offset/size: 0x258/8 +Protocol: 2.10+ + + This field, if nonzero, represents a preferred load address for the + kernel. A relocating bootloader should attempt to load at this + address if possible. + + A non-relocatable kernel will unconditionally move itself and to run + at this address. + +Field name: init_size +Type: read +Offset/size: 0x25c/4 + + This field indicates the amount of linear contiguous memory starting + at the kernel runtime start address that the kernel needs before it + is capable of examining its memory map. This is not the same thing + as the total amount of memory the kernel needs to boot, but it can + be used by a relocating boot loader to help select a safe load + address for the kernel. + + The kernel runtime start address is determined by the following algorithm: + + if (relocatable_kernel) + runtime_start = align_up(load_address, kernel_alignment) + else + runtime_start = pref_address + **** THE IMAGE CHECKSUM -- cgit v1.2.3 From 5031296c57024a78ddad4edfc993367dbf4abb98 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Thu, 7 May 2009 16:54:11 -0700 Subject: x86: add extension fields for bootloader type and version A long ago, in days of yore, it all began with a god named Thor. There were vikings and boats and some plans for a Linux kernel header. Unfortunately, a single 8-bit field was used for bootloader type and version. This has generally worked without *too* much pain, but we're getting close to flat running out of ID fields. Add extension fields for both type and version. The type will be extended if it the old field is 0xE; the version is a simple MSB extension. Keep /proc/sys/kernel/bootloader_type containing (type << 4) + (ver & 0xf) for backwards compatiblity, but also add /proc/sys/kernel/bootloader_version which contains the full version number. [ Impact: new feature to support more bootloaders ] Signed-off-by: H. Peter Anvin --- Documentation/x86/boot.txt | 59 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 52 insertions(+), 7 deletions(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt index cf8dfc70a11..8da3a795083 100644 --- a/Documentation/x86/boot.txt +++ b/Documentation/x86/boot.txt @@ -50,10 +50,9 @@ Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical pointer to single linked list of struct setup_data. -Protocol 2.10: (Kernel 2.6.31) A protocol for relaxed alignment +Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment beyond the kernel_alignment added, new init_size and - pref_address fields. - + pref_address fields. Added extended boot loader IDs. **** MEMORY LAYOUT @@ -173,7 +172,8 @@ Offset Proto Name Meaning 021C/4 2.00+ ramdisk_size initrd size (set by boot loader) 0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only 0224/2 2.01+ heap_end_ptr Free memory after setup end -0226/2 N/A pad1 Unused +0226/1 2.02+(3 ext_loader_ver Extended boot loader version +0227/1 2.02+(3 ext_loader_type Extended boot loader ID 0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line 022C/4 2.03+ ramdisk_max Highest legal initrd address 0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel @@ -197,6 +197,8 @@ Offset Proto Name Meaning field are unusable, which means the size of a bzImage kernel cannot be determined. +(3) Ignored, but safe to set, for boot protocols 2.02-2.09. + If the "HdrS" (0x53726448) magic number is not found at offset 0x202, the boot protocol version is "old". Loading an old kernel, the following parameters should be assumed: @@ -350,18 +352,32 @@ Protocol: 2.00+ 0xTV here, where T is an identifier for the boot loader and V is a version number. Otherwise, enter 0xFF here. + For boot loader IDs above T = 0xD, write T = 0xE to this field and + write the extended ID minus 0x10 to the ext_loader_type field. + Similarly, the ext_loader_ver field can be used to provide more than + four bits for the bootloader version. + + For example, for T = 0x15, V = 0x234, write: + + type_of_loader <- 0xE4 + ext_loader_type <- 0x05 + ext_loader_ver <- 0x23 + Assigned boot loader ids: 0 LILO (0x00 reserved for pre-2.00 bootloader) 1 Loadlin 2 bootsect-loader (0x20, all other values reserved) - 3 SYSLINUX - 4 EtherBoot + 3 Syslinux + 4 Etherboot/gPXE 5 ELILO 7 GRUB - 8 U-BOOT + 8 U-Boot 9 Xen A Gujin B Qemu + C Arcturus Networks uCbootloader + E Extended (see ext_loader_type) + F Special (0xFF = undefined) Please contact if you need a bootloader ID value assigned. @@ -460,6 +476,35 @@ Protocol: 2.01+ Set this field to the offset (from the beginning of the real-mode code) of the end of the setup stack/heap, minus 0x0200. +Field name: ext_loader_ver +Type: write (optional) +Offset/size: 0x226/1 +Protocol: 2.02+ + + This field is used as an extension of the version number in the + type_of_loader field. The total version number is considered to be + (type_of_loader & 0x0f) + (ext_loader_ver << 4). + + The use of this field is boot loader specific. If not written, it + is zero. + + Kernels prior to 2.6.31 did not recognize this field, but it is safe + to write for protocol version 2.02 or higher. + +Field name: ext_loader_type +Type: write (obligatory if (type_of_loader & 0xf0) == 0xe0) +Offset/size: 0x227/1 +Protocol: 2.02+ + + This field is used as an extension of the type number in + type_of_loader field. If the type in type_of_loader is 0xE, then + the actual type is (ext_loader_type + 0x10). + + This field is ignored if the type in type_of_loader is not 0xE. + + Kernels prior to 2.6.31 did not recognize this field, but it is safe + to write for protocol version 2.02 or higher. + Field name: cmd_line_ptr Type: write (obligatory) Offset/size: 0x228/4 -- cgit v1.2.3 From 888a589f6be07d624e21e2174d98375e9f95911b Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 15 May 2009 13:59:37 -0700 Subject: mm, x86: remove MEMORY_HOTPLUG_RESERVE related code after: | commit b263295dbffd33b0fbff670720fa178c30e3392a | Author: Christoph Lameter | Date: Wed Jan 30 13:30:47 2008 +0100 | | x86: 64-bit, make sparsemem vmemmap the only memory model we don't have MEMORY_HOTPLUG_RESERVE anymore. Historically, x86-64 had an architecture-specific method for memory hotplug whereby it scanned the SRAT for physical memory ranges that could be potentially used for memory hot-add later. By reserving those ranges without physical memory, the memmap would be allocated and left dormant until needed. This depended on the DISCONTIG memory model which has been removed so the code implementing HOTPLUG_RESERVE is now dead. This patch removes the dead code used by MEMORY_HOTPLUG_RESERVE. (Changelog authored by Mel.) v2: updated changelog, and remove hotadd= in doc [ Impact: remove dead code ] Signed-off-by: Yinghai Lu Reviewed-by: Christoph Lameter Reviewed-by: Mel Gorman Workflow-found-OK-by: Andrew Morton LKML-Reference: <4A0C4910.7090508@kernel.org> Signed-off-by: Ingo Molnar --- Documentation/x86/x86_64/boot-options.txt | 5 ----- 1 file changed, 5 deletions(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 34c13040a71..2db5893d6c9 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -150,11 +150,6 @@ NUMA Otherwise, the remaining system RAM is allocated to an additional node. - numa=hotadd=percent - Only allow hotadd memory to preallocate page structures upto - percent of already available memory. - numa=hotadd=0 will disable hotadd memory. - ACPI acpi=off Don't enable ACPI -- cgit v1.2.3 From 8780e8e0f6b34862cdf2c62d4d2674d6bc3207db Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 27 May 2009 21:56:56 +0200 Subject: x86, mce: improve documentation Document that check_interval set to 0 means no polling. Noticed by Hidetoshi Seto Also add a reference from boot options to the sysfs tunables Acked-by: Hidetoshi Seto Signed-off-by: Andi Kleen Signed-off-by: Hidetoshi Seto Signed-off-by: H. Peter Anvin --- Documentation/x86/x86_64/boot-options.txt | 2 ++ Documentation/x86/x86_64/machinecheck | 4 +++- 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 34c13040a71..63fca718256 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -5,6 +5,8 @@ only the AMD64 specific ones are listed here. Machine check + Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables. + mce=off disable machine check mce=bootlog Enable logging of machine checks left over from booting. Disabled by default on AMD because some BIOS leave bogus ones. diff --git a/Documentation/x86/x86_64/machinecheck b/Documentation/x86/x86_64/machinecheck index a05e58e7b15..a4fdb25446e 100644 --- a/Documentation/x86/x86_64/machinecheck +++ b/Documentation/x86/x86_64/machinecheck @@ -41,7 +41,9 @@ check_interval the polling interval. When the poller stops finding MCEs, it triggers an exponential backoff (poll less often) on the polling interval. The check_interval variable is both the initial and - maximum polling interval. + maximum polling interval. 0 means no polling for corrected machine + check errors (but some corrected errors might be still reported + in other ways) tolerant Tolerance level. When a machine check exception occurs for a non -- cgit v1.2.3 From 3c0797925f4ef9d55a32059d2af61a9c262e639d Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 27 May 2009 21:56:55 +0200 Subject: x86, mce: switch x86 machine check handler to Monarch election. On Intel platforms machine check exceptions are always broadcast to all CPUs. This patch makes the machine check handler synchronize all these machine checks, elect a Monarch to handle the event and collect the worst event from all CPUs and then process it first. This has some advantages: - When there is a truly data corrupting error the system panics as quickly as possible. This improves containment of corrupted data and makes sure the corrupted data never hits stable storage. - The panics are synchronized and do not reenter the panic code on multiple CPUs (which currently does not handle this well). - All the errors are reported. Currently it often happens that another CPU happens to do the panic first, but reports useless information (empty machine check) because the real error happened on another CPU which came in later. This is a big advantage on Nehalem where the 8 threads per CPU lead to often the wrong CPU winning the race and dumping useless information on a machine check. The problem also occurs in a less severe form on older CPUs. - The system can detect when no CPUs detected a machine check and shut down the system. This can happen when one CPU is so badly hung that that it cannot process a machine check anymore or when some external agent wants to stop the system by asserting the machine check pin. This follows Intel hardware recommendations. - This matches the recommended error model by the CPU designers. - The events can be output in true severity order - When a panic happens on another CPU it makes sure to be actually be able to process the stop IPI by enabling interrupts. The code is extremly careful to handle timeouts while waiting for other CPUs. It can't rely on the normal timing mechanisms (jiffies, ktime_get) because of its asynchronous/lockless nature, so it uses own timeouts using ndelay() and a "SPINUNIT" The timeout is configurable. By default it waits for upto one second for the other CPUs. This can be also disabled. From some informal testing AMD systems do not see to broadcast machine checks, so right now it's always disabled by default on non Intel CPUs or also on very old Intel systems. Includes fixes from Ying Huang Fixed a "ecception" in a comment (H.Seto) Moved global_nwo reset later based on suggestion from H.Seto v2: Avoid duplicate messages [ Impact: feature, fixes long standing problems. ] Signed-off-by: Andi Kleen Signed-off-by: Hidetoshi Seto Signed-off-by: H. Peter Anvin --- Documentation/x86/x86_64/boot-options.txt | 6 +++++- Documentation/x86/x86_64/machinecheck | 4 ++++ 2 files changed, 9 insertions(+), 1 deletion(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 63fca718256..0ee5e3b212f 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -15,13 +15,17 @@ Machine check in a reboot. On Intel systems it is enabled by default. mce=nobootlog Disable boot machine check logging. - mce=tolerancelevel (number) + mce=tolerancelevel[,monarchtimeout] (number,number) + tolerance levels: 0: always panic on uncorrected errors, log corrected errors 1: panic or SIGBUS on uncorrected errors, log corrected errors 2: SIGBUS or log uncorrected errors, log corrected errors 3: never panic or SIGBUS, log all errors (for testing only) Default is 1 Can be also set using sysfs which is preferable. + monarchtimeout: + Sets the time in us to wait for other CPUs on machine checks. 0 + to disable. nomce (for compatibility with i386): same as mce=off diff --git a/Documentation/x86/x86_64/machinecheck b/Documentation/x86/x86_64/machinecheck index a4fdb25446e..b1fb3027328 100644 --- a/Documentation/x86/x86_64/machinecheck +++ b/Documentation/x86/x86_64/machinecheck @@ -69,6 +69,10 @@ trigger Program to run when a machine check event is detected. This is an alternative to running mcelog regularly from cron and allows to detect events faster. +monarch_timeout + How long to wait for the other CPUs to machine check too on a + exception. 0 to disable waiting for other CPUs. + Unit: us TBD document entries for AMD threshold interrupt configuration -- cgit v1.2.3 From 62fdac5913f71f8f200bd2c9bd59a02e9a1498e9 Mon Sep 17 00:00:00 2001 From: Hidetoshi Seto Date: Thu, 11 Jun 2009 16:06:07 +0900 Subject: x86, mce: Add boot options for corrected errors This patch introduces three boot options (no_cmci, dont_log_ce and ignore_ce) to control handling for corrected errors. The "mce=no_cmci" boot option disables the CMCI feature. Since CMCI is a new feature so having boot controls to disable it will be a help if the hardware is misbehaving. The "mce=dont_log_ce" boot option disables logging for corrected errors. All reported corrected errors will be cleared silently. This option will be useful if you never care about corrected errors. The "mce=ignore_ce" boot option disables features for corrected errors, i.e. polling timer and cmci. All corrected events are not cleared and kept in bank MSRs. Usually this disablement is not recommended, however it will be a help if there are some conflict with the BIOS or hardware monitoring applications etc., that clears corrected events in banks instead of OS. [ And trivial cleanup (space -> tab) for doc is included. ] Signed-off-by: Hidetoshi Seto Reviewed-by: Andi Kleen LKML-Reference: <4A30ACDF.5030408@jp.fujitsu.com> Signed-off-by: Ingo Molnar --- Documentation/x86/x86_64/boot-options.txt | 36 +++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-) (limited to 'Documentation/x86') diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 0ee5e3b212f..fa2bed07d21 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -7,12 +7,36 @@ Machine check Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables. - mce=off disable machine check - mce=bootlog Enable logging of machine checks left over from booting. - Disabled by default on AMD because some BIOS leave bogus ones. - If your BIOS doesn't do that it's a good idea to enable though - to make sure you log even machine check events that result - in a reboot. On Intel systems it is enabled by default. + mce=off + Disable machine check + mce=no_cmci + Disable CMCI(Corrected Machine Check Interrupt) that + Intel processor supports. Usually this disablement is + not recommended, but it might be handy if your hardware + is misbehaving. + Note that you'll get more problems without CMCI than with + due to the shared banks, i.e. you might get duplicated + error logs. + mce=dont_log_ce + Don't make logs for corrected errors. All events reported + as corrected are silently cleared by OS. + This option will be useful if you have no interest in any + of corrected errors. + mce=ignore_ce + Disable features for corrected errors, e.g. polling timer + and CMCI. All events reported as corrected are not cleared + by OS and remained in its error banks. + Usually this disablement is not recommended, however if + there is an agent checking/clearing corrected errors + (e.g. BIOS or hardware monitoring applications), conflicting + with OS's error handling, and you cannot deactivate the agent, + then this option will be a help. + mce=bootlog + Enable logging of machine checks left over from booting. + Disabled by default on AMD because some BIOS leave bogus ones. + If your BIOS doesn't do that it's a good idea to enable though + to make sure you log even machine check events that result + in a reboot. On Intel systems it is enabled by default. mce=nobootlog Disable boot machine check logging. mce=tolerancelevel[,monarchtimeout] (number,number) -- cgit v1.2.3