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Documentation / acpi / apei / einj.txt




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Based on kernel version 4.1. Page generated on 2015-06-28 12:07 EST.

1				APEI Error INJection
2				~~~~~~~~~~~~~~~~~~~~
3	
4	EINJ provides a hardware error injection mechanism. It is very useful
5	for debugging and testing APEI and RAS features in general.
6	
7	You need to check whether your BIOS supports EINJ first. For that, look
8	for early boot messages similar to this one:
9	
10	ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL           00000001 INTL 00000001)
11	
12	which shows that the BIOS is exposing an EINJ table - it is the
13	mechanism through which the injection is done.
14	
15	Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
16	which is a different representation of the same thing.
17	
18	It doesn't necessarily mean that EINJ is not supported if those above
19	don't exist: before you give up, go into BIOS setup to see if the BIOS
20	has an option to enable error injection. Look for something called WHEA
21	or similar. Often, you need to enable an ACPI5 support option prior, in
22	order to see the APEI,EINJ,... functionality supported and exposed by
23	the BIOS menu.
24	
25	To use EINJ, make sure the following are options enabled in your kernel
26	configuration:
27	
28	CONFIG_DEBUG_FS
29	CONFIG_ACPI_APEI
30	CONFIG_ACPI_APEI_EINJ
31	
32	The EINJ user interface is in <debugfs mount point>/apei/einj.
33	
34	The following files belong to it:
35	
36	- available_error_type
37	
38	  This file shows which error types are supported:
39	
40	  Error Type Value	Error Description
41	  ================	=================
42	  0x00000001		Processor Correctable
43	  0x00000002		Processor Uncorrectable non-fatal
44	  0x00000004		Processor Uncorrectable fatal
45	  0x00000008		Memory Correctable
46	  0x00000010		Memory Uncorrectable non-fatal
47	  0x00000020		Memory Uncorrectable fatal
48	  0x00000040		PCI Express Correctable
49	  0x00000080		PCI Express Uncorrectable fatal
50	  0x00000100		PCI Express Uncorrectable non-fatal
51	  0x00000200		Platform Correctable
52	  0x00000400		Platform Uncorrectable non-fatal
53	  0x00000800		Platform Uncorrectable fatal
54	
55	  The format of the file contents are as above, except present are only
56	  the available error types.
57	
58	- error_type
59	
60	  Set the value of the error type being injected. Possible error types
61	  are defined in the file available_error_type above.
62	
63	- error_inject
64	
65	  Write any integer to this file to trigger the error injection. Make
66	  sure you have specified all necessary error parameters, i.e. this
67	  write should be the last step when injecting errors.
68	
69	- flags
70	
71	  Present for kernel versions 3.13 and above. Used to specify which
72	  of param{1..4} are valid and should be used by the firmware during
73	  injection. Value is a bitmask as specified in ACPI5.0 spec for the
74	  SET_ERROR_TYPE_WITH_ADDRESS data structure:
75	
76		Bit 0 - Processor APIC field valid (see param3 below).
77		Bit 1 - Memory address and mask valid (param1 and param2).
78		Bit 2 - PCIe (seg,bus,dev,fn) valid (see param4 below).
79	
80	  If set to zero, legacy behavior is mimicked where the type of
81	  injection specifies just one bit set, and param1 is multiplexed.
82	
83	- param1
84	
85	  This file is used to set the first error parameter value. Its effect
86	  depends on the error type specified in error_type. For example, if
87	  error type is memory related type, the param1 should be a valid
88	  physical memory address. [Unless "flag" is set - see above]
89	
90	- param2
91	
92	  Same use as param1 above. For example, if error type is of memory
93	  related type, then param2 should be a physical memory address mask.
94	  Linux requires page or narrower granularity, say, 0xfffffffffffff000.
95	
96	- param3
97	
98	  Used when the 0x1 bit is set in "flags" to specify the APIC id
99	
100	- param4
101	  Used when the 0x4 bit is set in "flags" to specify target PCIe device
102	
103	- notrigger
104	
105	  The error injection mechanism is a two-step process. First inject the
106	  error, then perform some actions to trigger it. Setting "notrigger"
107	  to 1 skips the trigger phase, which *may* allow the user to cause the
108	  error in some other context by a simple access to the CPU, memory
109	  location, or device that is the target of the error injection. Whether
110	  this actually works depends on what operations the BIOS actually
111	  includes in the trigger phase.
112	
113	BIOS versions based on the ACPI 4.0 specification have limited options
114	in controlling where the errors are injected. Your BIOS may support an
115	extension (enabled with the param_extension=1 module parameter, or boot
116	command line einj.param_extension=1). This allows the address and mask
117	for memory injections to be specified by the param1 and param2 files in
118	apei/einj.
119	
120	BIOS versions based on the ACPI 5.0 specification have more control over
121	the target of the injection. For processor-related errors (type 0x1, 0x2
122	and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
123	param2 for bit 1) so that you have more information added to the error
124	signature being injected. The actual data passed is this:
125	
126		memory_address = param1;
127		memory_address_range = param2;
128		apicid = param3;
129		pcie_sbdf = param4;
130	
131	For memory errors (type 0x8, 0x10 and 0x20) the address is set using
132	param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
133	express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
134	function are specified using param1:
135	
136	         31     24 23    16 15    11 10      8  7        0
137		+-------------------------------------------------+
138		| segment |   bus  | device | function | reserved |
139		+-------------------------------------------------+
140	
141	Anyway, you get the idea, if there's doubt just take a look at the code
142	in drivers/acpi/apei/einj.c.
143	
144	An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
145	In this case a file named vendor will contain identifying information
146	from the BIOS that hopefully will allow an application wishing to use
147	the vendor-specific extension to tell that they are running on a BIOS
148	that supports it. All vendor extensions have the 0x80000000 bit set in
149	error_type. A file vendor_flags controls the interpretation of param1
150	and param2 (1 = PROCESSOR, 2 = MEMORY, 4 = PCI). See your BIOS vendor
151	documentation for details (and expect changes to this API if vendors
152	creativity in using this feature expands beyond our expectations).
153	
154	
155	An error injection example:
156	
157	# cd /sys/kernel/debug/apei/einj
158	# cat available_error_type		# See which errors can be injected
159	0x00000002	Processor Uncorrectable non-fatal
160	0x00000008	Memory Correctable
161	0x00000010	Memory Uncorrectable non-fatal
162	# echo 0x12345000 > param1		# Set memory address for injection
163	# echo $((-1 << 12)) > param2		# Mask 0xfffffffffffff000 - anywhere in this page
164	# echo 0x8 > error_type			# Choose correctable memory error
165	# echo 1 > error_inject			# Inject now
166	
167	You should see something like this in dmesg:
168	
169	[22715.830801] EDAC sbridge MC3: HANDLING MCE MEMORY ERROR
170	[22715.834759] EDAC sbridge MC3: CPU 0: Machine Check Event: 0 Bank 7: 8c00004000010090
171	[22715.834759] EDAC sbridge MC3: TSC 0
172	[22715.834759] EDAC sbridge MC3: ADDR 12345000 EDAC sbridge MC3: MISC 144780c86
173	[22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
174	[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)
175	
176	For more information about EINJ, please refer to ACPI specification
177	version 4.0, section 17.5 and ACPI 5.0, section 18.6.
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