Re: [ndctl PATCH v3 7/7] Documentation: Add docs for inject/clear-error commands

Dave Jiang
2025-10-22T17:22:26Z

On 10/21/25 11:31 AM, Ben Cheatham wrote:
> 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>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>> ---
> Documentation/cxl/cxl-clear-error.txt | 67 +++++++++++++
> Documentation/cxl/cxl-inject-error.txt | 129 +++++++++++++++++++++++++
> Documentation/cxl/meson.build | 2 +
> 3 files changed, 198 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..ccb0e63
> --- /dev/null
> +++ b/Documentation/cxl/cxl-clear-error.txt
> @@ -0,0 +1,67 @@
> +// 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":[
> + ]
> +}
> +
> +----
> +
> +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..e1bebd7
> --- /dev/null
> +++ b/Documentation/cxl/cxl-inject-error.txt
> @@ -0,0 +1,129 @@
> +// 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>]
> +
> +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 CXL 2.0+ ports are dports of ports at depth 1 in the output of cxl-list.
> +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 with the '-N' option of 'cxl-list' under a CXL bus object. For example:
> +
> +----
> +
> +# cxl list -NB
> +[
> + {
> + "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.
> +
> +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 devices support poison injection. To see if a device supports poison injection
> +through debugfs, use 'cxl-list' with the '-N' option and look for the "poison-injectable"
> +attribute under the device. Example:
> +
> +----
> +
> +# cxl list -Nu -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-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