intel_reg(1)

Name
intel_reg - Intel graphics register multitool

SYNOPSIS

intel_reg [OPTIONS] COMMAND

DESCRIPTION

Intel graphics register multitool. Read, write, dump, and decode Intel graphics MMIO and sideband registers, and more.

OPTIONS

Some options are global, and some specific to commands.

--verbose
    Increase verbosity.

--quiet
    Decrease verbosity.

--count=N
    Read N registers.

--binary
    Output binary values.

--decode
    Decode registers. By default it only uses the raw offsets, unless it's a command that would otherwise not work without it or another option forces it enabled. See COMMANDS below for details.

--all
    Decode registers for all known platforms. This option implies --decode.

--mmio=FILE
    Use MMIO bar from FILE.

--devid=DEVID
    Pretend to be PCI ID DEVID. Useful with MMIO bar snapshots from other machines.

--pci-slot <domain>:<bus>:<device>[.<func>]
    Find Intel GPU by PCI slot. Useful with multi-GPU hardware.

--spec=PATH
    Read register spec from directory or file specified by PATH; see REGISTER SPEC DEFINITIONS below for details. This option implies --decode.

--help
    Show brief help.

COMMANDS

See REGISTER REFERENCES below on how to describe registers for the commands.

  read [--count=N] REGISTER [...]

Dump each specified REGISTER, or N registers starting from each REGISTER.

  write REGISTER VALUE [REGISTER VALUE ...]

Write each VALUE to corresponding REGISTER.

  dump [--mmio=FILE --devid=DEVID]

Dump all registers specified in the register spec. The option --decode is implicitly enabled.

  decode REGISTER VALUE

Decode REGISTER VALUE. The option --decode is implicitly enabled.

  list

List the known registers. The option --decode is implicitly enabled.

  help

Display brief help.

REGISTER REFERENCES

Registers are defined as [(PORTNAME|PORTNUM|ENGINE|MMIO-OFFSET):](REGNAME|REGADDR).

PORTNAME
    The register access method, most often MMIO, which is the default. The methods supported on all platforms are "mmio", "portio-vga", and "mmio-vga".

    On BYT and CHV, the sideband ports "bunit", "punit", "nc", "dpio", "gpio-nc", "cck", "ccu", "dpio2", and "flisdsi" are also supported.

PORTNUM
    Port number for the sideband ports supported on BYT and CHV. Only numbers mapped to the supported ports are allowed, arbitrary numbers are not accepted.

    Numbers above 0xff are automatically interpreted as MMIO offsets, not port numbers.

ENGINE
    Instead of cpu based MMIO, specified engine can be used for access method. Batchbuffer will be targeted for the engine to do read/write. The list of available engines is architecture specific and can be found with "intel_reg help". Prefixing engine name with '-' uses non-privileged batchbuffer for access.

MMIO-OFFSET
    Use MMIO, and add this offset to the register address.

    Numbers equal to or below 0xff are automatically interpreted as port numbers, not MMIO offsets.

REGNAME
    Name of the register as defined in the register spec.

    If MMIO offset is not specified, it is picked up from the register spec. However, ports are not; the port is a namespace for the register names.

REGADDR
    Register address. The corresponding register name need not be specified in the register spec.

ENVIRONMENT

INTEL_REG_SPEC
    Path to a directory or a file containing register spec definitions.

REGISTER SPEC DEFINITIONS

A register spec associates register names with addresses. The spec is searched for in this order:

1.  Directory or file specified by the --spec option.

2.  Directory or file specified by the INTEL_REG_SPEC environment variable.

3.  Builtin register spec. Also used as fallback with a warning if the above are used but fail.

    If a directory is specified using --spec option or INTEL_REG_SPEC environment variable, the directory is scanned for a spec file in this order:

1.  File named after the PCI device id. For example, "0412".

2.  File named after the code name in lowercase, without punctuation. For example, "valleyview".

3.  File named after generation. For example, "gen7" (note that this matches valleyview, ivybridge and haswell!).

  Register Spec File Format

The register spec format is briefly described below:

•   Empty lines and lines beginning with "#", ";", or "//" are ignored.

•   Lines not beginning with "(" are interpreted as file names, absolute or relative, to be included.

•   Lines beginning with "(" are interpreted as register definitions.

    Registers are defined as tuples ('REGNAME', 'REGADDR', 'PORTNAME|PORTNUM|MMIO-OFFSET'), as in REGISTER REFERENCES above. The port description may also be an empty string to denote MMIO.

    Examples:

•   # this is a comment, below is an include

•   vlv_pipe_a.txt

•   ('GEN6_PMINTRMSK', '0x0000a168', '')

•   ('MIPIA_PORT_CTRL', '0x61190', '0x180000')

•   ('PLL1_DW0', '0x8000', 'DPIO')

BUGS

Reading some registers may hang the GPU or the machine.

REPORTING BUGS

Report bugs on fd.o GitLab: <https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/issues>

Author
Jani Nikula <jani.nikula@intel.com>

Copyright
2015-2025 Intel Corporation