path: root/Documentation/firmware-guide
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authorChangbin Du <>2019-04-25 01:53:02 +0800
committerRafael J. Wysocki <>2019-04-25 23:07:20 +0200
commit440ebec745dcbc44866f6b19e5145a12d4494a5f (patch)
treece677c0acc7f8d593056668a3e9274f350a6a706 /Documentation/firmware-guide
parentdeb95169ef4279362f4c6167c4c59c8d68711d97 (diff)
Documentation: ACPI: move apei/einj.txt to firmware-guide/acpi and convert to reST
This converts the plain text documentation to reStructuredText format and adds it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du <> Reviewed-by: Mauro Carvalho Chehab <> Signed-off-by: Rafael J. Wysocki <>
Diffstat (limited to 'Documentation/firmware-guide')
2 files changed, 186 insertions, 0 deletions
diff --git a/Documentation/firmware-guide/acpi/apei/einj.rst b/Documentation/firmware-guide/acpi/apei/einj.rst
new file mode 100644
index 000000000000..e588bccf5158
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+++ b/Documentation/firmware-guide/acpi/apei/einj.rst
@@ -0,0 +1,185 @@
+.. SPDX-License-Identifier: GPL-2.0
+APEI Error INJection
+EINJ provides a hardware error injection mechanism. It is very useful
+for debugging and testing APEI and RAS features in general.
+You need to check whether your BIOS supports EINJ first. For that, look
+for early boot messages similar to this one::
+ ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL 00000001 INTL 00000001)
+which shows that the BIOS is exposing an EINJ table - it is the
+mechanism through which the injection is done.
+Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
+which is a different representation of the same thing.
+It doesn't necessarily mean that EINJ is not supported if those above
+don't exist: before you give up, go into BIOS setup to see if the BIOS
+has an option to enable error injection. Look for something called WHEA
+or similar. Often, you need to enable an ACPI5 support option prior, in
+order to see the APEI,EINJ,... functionality supported and exposed by
+the BIOS menu.
+To use EINJ, make sure the following are options enabled in your kernel
+The EINJ user interface is in <debugfs mount point>/apei/einj.
+The following files belong to it:
+- available_error_type
+ This file shows which error types are supported:
+ ================ ===================================
+ Error Type Value Error Description
+ ================ ===================================
+ 0x00000001 Processor Correctable
+ 0x00000002 Processor Uncorrectable non-fatal
+ 0x00000004 Processor Uncorrectable fatal
+ 0x00000008 Memory Correctable
+ 0x00000010 Memory Uncorrectable non-fatal
+ 0x00000020 Memory Uncorrectable fatal
+ 0x00000040 PCI Express Correctable
+ 0x00000080 PCI Express Uncorrectable fatal
+ 0x00000100 PCI Express Uncorrectable non-fatal
+ 0x00000200 Platform Correctable
+ 0x00000400 Platform Uncorrectable non-fatal
+ 0x00000800 Platform Uncorrectable fatal
+ ================ ===================================
+ The format of the file contents are as above, except present are only
+ the available error types.
+- error_type
+ Set the value of the error type being injected. Possible error types
+ are defined in the file available_error_type above.
+- error_inject
+ Write any integer to this file to trigger the error injection. Make
+ sure you have specified all necessary error parameters, i.e. this
+ write should be the last step when injecting errors.
+- flags
+ Present for kernel versions 3.13 and above. Used to specify which
+ of param{1..4} are valid and should be used by the firmware during
+ injection. Value is a bitmask as specified in ACPI5.0 spec for the
+ Bit 0
+ Processor APIC field valid (see param3 below).
+ Bit 1
+ Memory address and mask valid (param1 and param2).
+ Bit 2
+ PCIe (seg,bus,dev,fn) valid (see param4 below).
+ If set to zero, legacy behavior is mimicked where the type of
+ injection specifies just one bit set, and param1 is multiplexed.
+- param1
+ This file is used to set the first error parameter value. Its effect
+ depends on the error type specified in error_type. For example, if
+ error type is memory related type, the param1 should be a valid
+ physical memory address. [Unless "flag" is set - see above]
+- param2
+ Same use as param1 above. For example, if error type is of memory
+ related type, then param2 should be a physical memory address mask.
+ Linux requires page or narrower granularity, say, 0xfffffffffffff000.
+- param3
+ Used when the 0x1 bit is set in "flags" to specify the APIC id
+- param4
+ Used when the 0x4 bit is set in "flags" to specify target PCIe device
+- notrigger
+ The error injection mechanism is a two-step process. First inject the
+ error, then perform some actions to trigger it. Setting "notrigger"
+ to 1 skips the trigger phase, which *may* allow the user to cause the
+ error in some other context by a simple access to the CPU, memory
+ location, or device that is the target of the error injection. Whether
+ this actually works depends on what operations the BIOS actually
+ includes in the trigger phase.
+BIOS versions based on the ACPI 4.0 specification have limited options
+in controlling where the errors are injected. Your BIOS may support an
+extension (enabled with the param_extension=1 module parameter, or boot
+command line einj.param_extension=1). This allows the address and mask
+for memory injections to be specified by the param1 and param2 files in
+BIOS versions based on the ACPI 5.0 specification have more control over
+the target of the injection. For processor-related errors (type 0x1, 0x2
+and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
+param2 for bit 1) so that you have more information added to the error
+signature being injected. The actual data passed is this::
+ memory_address = param1;
+ memory_address_range = param2;
+ apicid = param3;
+ pcie_sbdf = param4;
+For memory errors (type 0x8, 0x10 and 0x20) the address is set using
+param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
+express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
+function are specified using param1::
+ 31 24 23 16 15 11 10 8 7 0
+ +-------------------------------------------------+
+ | segment | bus | device | function | reserved |
+ +-------------------------------------------------+
+Anyway, you get the idea, if there's doubt just take a look at the code
+in drivers/acpi/apei/einj.c.
+An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
+In this case a file named vendor will contain identifying information
+from the BIOS that hopefully will allow an application wishing to use
+the vendor-specific extension to tell that they are running on a BIOS
+that supports it. All vendor extensions have the 0x80000000 bit set in
+error_type. A file vendor_flags controls the interpretation of param1
+and param2 (1 = PROCESSOR, 2 = MEMORY, 4 = PCI). See your BIOS vendor
+documentation for details (and expect changes to this API if vendors
+creativity in using this feature expands beyond our expectations).
+An error injection example::
+ # cd /sys/kernel/debug/apei/einj
+ # cat available_error_type # See which errors can be injected
+ 0x00000002 Processor Uncorrectable non-fatal
+ 0x00000008 Memory Correctable
+ 0x00000010 Memory Uncorrectable non-fatal
+ # echo 0x12345000 > param1 # Set memory address for injection
+ # echo $((-1 << 12)) > param2 # Mask 0xfffffffffffff000 - anywhere in this page
+ # echo 0x8 > error_type # Choose correctable memory error
+ # echo 1 > error_inject # Inject now
+You should see something like this in dmesg::
+ [22715.830801] EDAC sbridge MC3: HANDLING MCE MEMORY ERROR
+ [22715.834759] EDAC sbridge MC3: CPU 0: Machine Check Event: 0 Bank 7: 8c00004000010090
+ [22715.834759] EDAC sbridge MC3: TSC 0
+ [22715.834759] EDAC sbridge MC3: ADDR 12345000 EDAC sbridge MC3: MISC 144780c86
+ [22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
+ [22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 - area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)
+For more information about EINJ, please refer to ACPI specification
+version 4.0, section 17.5 and ACPI 5.0, section 18.6.
diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst
index 869badba6d7a..fca854f017d8 100644
--- a/Documentation/firmware-guide/acpi/index.rst
+++ b/Documentation/firmware-guide/acpi/index.rst
@@ -18,6 +18,7 @@ ACPI Support
+ apei/einj