'\" t
.\"     Title: nvme-set-reg
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/30/2026
.\"    Manual: NVMe Manual
.\"    Source: NVMe
.\"  Language: English
.\"
.TH "NVME\-SET\-REG" "1" "10/30/2026" "NVMe" "NVMe Manual"
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.SH "NAME"
nvme-set-reg \- Writes and shows the defined NVMe controller register
.SH "SYNOPSIS"
.sp
.nf
\fInvme\fR [<global\-options>] \fIset\-reg\fR <device>
                        [\-\-register=<name> | \-r <name>] [\-\-offset=<offset> | \-O <offset>]
                        [\-\-value=<val> | \-V <val>] [\-\-mmio32 | \-m]
.fi
.SH "DESCRIPTION"
.sp
Writes a controller register: of an NVMe over PCIe controller in its PCI memory space, of an NVMe over Fabrics controller, which has no PCI memory space, the property with a Property Set command\&.
.sp
The <device> parameter is mandatory and must be the nvme admin character device (ex: /dev/nvme0)\&.
.SH "OPTIONS"
.PP
\-r <name>, \-\-register=<name>
.RS 4
The register to write, by name: one of the registers the host may write, intms, intmc, cc, csts, nssr, aqa, asq, acq, bprsel, bpmbl, cmbmsc, nssd, pmrctl, pmrmscl, pmrmscu\&.
.RE
.PP
\-O <offset>, \-\-offset=<offset>
.RS 4
The register to write, by offset or name, e\&.g\&. 0x14 or cc\&.
.RE
.PP
\-V <val>, \-\-value=<val>
.RS 4
The value to write\&. A 32 bit register refuses a larger value\&.
.RE
.PP
\-m, \-\-mmio32
.RS 4
Write a 64 bit register as two 32 bit accesses\&.
.RE
.sp
The options \-\-cc=<val>, \-\-aqa=<val> and so on of earlier versions, one for each register the host may write, still work, but are deprecated: use \-\-register and \-\-value\&.
.SH "GLOBAL OPTIONS"
.sp
The following options are defined at the top\-level nvme command and are available to this subcommand:
.PP
\-\-dry\-run
.RS 4
Print the command that would be executed, but do not actually execute it\&.
.RE
.PP
\-\-no\-ioctl\-probing
.RS 4
Disable probing for 64\-bit IOCTL support\&.
.RE
.PP
\-\-no\-retries
.RS 4
Disable retry logic on transient errors\&.
.RE
.PP
\-o <fmt>, \-\-output\-format=<fmt>
.RS 4
Set the reporting format to
\fInormal\fR,
\fItabular, \*(Aqjson\fR, or
\fIbinary\fR\&. Only one output format may be used at a time\&.
.RE
.PP
\-\-output\-format\-version=<version>
.RS 4
Select the output format version\&. Version
\fI1\fR
uses the original field naming, while version
\fI2\fR
(default) provides more consistent and script\-friendly field names\&. Other versions are rejected\&.
.RE
.PP
\-\-quiet
.RS 4
Suppress informational messages\&. Errors are still reported, and \-\-quiet cancels any \-\-verbose for the library log level\&.
.RE
.PP
\-\-set\-options=<key=value>[,<key=value>\&...]
.RS 4
Set libnvme library options for this invocation\&. Supported keys are
\fIforce\-4k\fR,
\fImi\-probe\-enabled\fR,
\fItest\-base\-dir\fR
and
\fItest\-sysfs\-dir\fR\&.
.RE
.PP
\-\-timeout=<ms>
.RS 4
Set the timeout for the command in milliseconds\&.
\fIinfinite\fR
or
\fI\-1\fR
waits without a time limit (0xffffffff)\&.
.RE
.PP
\-v, \-\-verbose
.RS 4
Increase the level of detail in the output\&. May be specified multiple times to further increase verbosity\&.
.RE
.sp
These options can also be set as machine\-wide defaults in nvme\-cli\&.conf(5)\&. A command\-line flag always overrides the file\&.
.SH "EXAMPLES"
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Write 0x460000 to the Controller Configuration register
.sp
.if n \{\
.RS 4
.\}
.nf
# nvme set\-reg /dev/nvme0 \-\-register=cc \-\-value=0x460000
.fi
.if n \{\
.RE
.\}
.RE
.SH "NVME"
.sp
Part of the nvme\-user suite\&.