[PATCH 7/7] Documentation: Add docs for inject/clear-error commands

Ben Cheatham
2026-01-09T16:07:35Z

Add man pages for the 'cxl-inject-error' and 'cxl-clear-error' commands.
These man pages show usage and examples for each of their use cases.

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
Documentation/cxl/cxl-clear-error.txt | 69 +++++++++++
Documentation/cxl/cxl-inject-error.txt | 161 +++++++++++++++++++++++++
Documentation/cxl/meson.build | 2 +
3 files changed, 232 insertions(+)
create mode 100644 Documentation/cxl/cxl-clear-error.txt
create mode 100644 Documentation/cxl/cxl-inject-error.txt

diff --git a/Documentation/cxl/cxl-clear-error.txt b/Documentation/cxl/cxl-clear-error.txt
new file mode 100644
index 0000000..9d77855
--- /dev/null
+++ b/Documentation/cxl/cxl-clear-error.txt
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+
+cxl-clear-error(1)
+==================
+
+NAME
+----
+cxl-clear-error - Clear CXL errors from CXL devices
+
+SYNOPSIS
+--------
+[verse]
+'cxl clear-error' <device name> [<options>]
+
+Clear an error from a CXL device. The types of devices supported are:
+
+"memdevs":: A CXL memory device. Memory devices are specified by device
+name ("mem0"), device id ("0") and/or host device name ("0000:35:00.0").
+
+Only device poison (viewable using the '-L'/'--media-errors' option of
+'cxl-list') can be cleared from a device using this command. For example:
+
+----
+
+# cxl list -m mem0 -L -u
+{
+ "memdev":"mem0",
+ "ram_size":"1024.00 MiB (1073.74 MB)",
+ "ram_qos_class":42,
+ "serial":"0x0",
+ "numa_node:1,
+ "host":"0000:35:00.0",
+ "media_errors":[
+ {
+ "offset":"0x1000",
+ "length":64,
+ "source":"Injected"
+ }
+ ]
+}
+
+# cxl clear-error mem0 -a 0x1000
+poison cleared at mem0:0x1000
+
+# cxl list -m mem0 -L -u
+{
+ "memdev":"mem0",
+ "ram_size":"1024.00 MiB (1073.74 MB)",
+ "ram_qos_class":42,
+ "serial":"0x0",
+ "numa_node:1,
+ "host":"0000:35:00.0",
+ "media_errors":[
+ ]
+}
+
+----
+
+This command depends on the kernel debug filesystem (debugfs) to clear device poison.
+
+OPTIONS
+-------
+-a::
+--address::
+ Device physical address (DPA) to clear poison from. Address can be specified
+ in hex or decimal. Required for clearing poison.
+
+--debug::
+ Enable debug output
diff --git a/Documentation/cxl/cxl-inject-error.txt b/Documentation/cxl/cxl-inject-error.txt
new file mode 100644
index 0000000..80d03be
--- /dev/null
+++ b/Documentation/cxl/cxl-inject-error.txt
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+
+cxl-inject-error(1)
+===================
+
+NAME
+----
+cxl-inject-error - Inject CXL errors into CXL devices
+
+SYNOPSIS
+--------
+[verse]
+'cxl inject-error' <device name> [<options>]
+
+WARNING: Error injection can cause system instability and should only be used
+for debugging hardware and software error recovery flows. Use at your own risk!
+
+Inject an error into a CXL device. The type of errors supported depend on the
+device specified. The types of devices supported are:
+
+"Downstream Ports":: A CXL RCH downstream port (dport) or a CXL VH root port.
+Eligible ports will have their 'protocol_injectable' attribute in 'cxl-list'
+set to true. Dports are specified by host name ("0000:0e:01.1").
+"memdevs":: A CXL memory device. Memory devices are specified by device name
+("mem0"), device id ("0"), and/or host device name ("0000:35:00.0").
+
+There are two types of errors which can be injected: CXL protocol errors
+and device poison.
+
+CXL protocol errors can only be used with downstream ports (as defined above).
+Protocol errors follow the format of "<protocol>-<severity>". For example,
+a "mem-fatal" error is a CXL.mem fatal protocol error. Protocol errors can be
+found in the "injectable_protocol_errors" list under a CXL bus object. This
+list is only available when the CXL debugfs is accessible (normally mounted
+at "/sys/kernel/debug/cxl"). For example:
+
+----
+
+# cxl list -B
+[
+ {
+ "bus":"root0",
+ "provider":"ACPI.CXL",
+ "injectable_protocol_errors":[
+ "mem-correctable",
+ "mem-fatal",
+ ]
+ }
+]
+
+----
+
+CXL protocol (CXL.cache/mem) error injection requires the platform to support
+ACPI v6.5+ error injection (EINJ). In addition to platform support, the
+CONFIG_ACPI_APEI_EINJ and CONFIG_ACPI_APEI_EINJ_CXL kernel configuration options
+will need to be enabled. For more information, view the Linux kernel documentation
+on EINJ. Example using the bus output above:
+
+----
+
+# cxl list -TP
+ [
+ {
+ "port":"port1",
+ "host":"pci0000:e0",
+ "depth":1,
+ "decoders_committed":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:e0:01.1",
+ "alias":"device:02",
+ "id":0,
+ "protocol_injectable":true
+ }
+ ]
+ }
+]
+
+# cxl inject-error "0000:e0:01.1" -t mem-correctable
+cxl inject-error: inject_proto_err: injected mem-correctable protocol error.
+
+----
+
+Device poison can only by used with CXL memory devices. A device physical address
+(DPA) is required to do poison injection. DPAs range from 0 to the size of
+device's memory, which can be found using 'cxl-list'. An example injection:
+
+----
+
+# cxl inject-error mem0 -t poison -a 0x1000
+poison injected at mem0:0x1000
+# cxl list -m mem0 -u --media-errors
+{
+ "memdev":"mem0",
+ "ram_size":"256.00 MiB (268.44 MB)",
+ "serial":"0",
+ "host":"0000:0d:00.0",
+ "firmware_version":"BWFW VERSION 00",
+ "media_errors":[
+ {
+ "offset":"0x1000",
+ "length":64,
+ "source":"Injected"
+ }
+ ]
+}
+
+----
+
+Not all memory devices support poison injection. To see if a device supports
+poison injection through debugfs, use 'cxl-list' look for the "poison-injectable"
+attribute under the device. This attribute is only available when the CXL debugfs
+is accessible. Example:
+
+----
+
+# cxl list -u -m mem0
+{
+ "memdev":"mem0",
+ "ram_size":"256.00 MiB (268.44 MB)",
+ "serial":"0",
+ "host":"0000:0d:00.0",
+ "firmware_version":"BWFW VERSION 00",
+ "poison_injectable":true
+}
+
+----
+
+This command depends on the kernel debug filesystem (debugfs) to do CXL protocol
+error and device poison injection.
+
+OPTIONS
+-------
+-a::
+--address::
+ Device physical address (DPA) to use for poison injection. Address can
+ be specified in hex or decimal. Required for poison injection.
+
+-t::
+--type::
+ Type of error to inject into <device name>. The type of error is restricted
+ by device type. The following shows the possible types under their associated
+ device type(s):
+----
+
+Downstream Ports: ::
+ cache-correctable, cache-uncorrectable, cache-fatal, mem-correctable,
+ mem-uncorrectable, mem-fatal
+
+Memdevs: ::
+ poison
+
+----
+
+--debug::
+ Enable debug output
+
+SEE ALSO
+--------
+linkcxl:cxl-list[1]
diff --git a/Documentation/cxl/meson.build b/Documentation/cxl/meson.build
index 8085c1c..0b75eed 100644
--- a/Documentation/cxl/meson.build
+++ b/Documentation/cxl/meson.build
@@ -50,6 +50,8 @@ cxl_manpages = [
'cxl-update-firmware.txt',
'cxl-set-alert-config.txt',
'cxl-wait-sanitize.txt',
+ 'cxl-inject-error.txt',
+ 'cxl-clear-error.txt',
]

foreach man : cxl_manpages
--
2.52.0