NAME¶

iucode_tool - Tool to manipulate Intel® IA-32/X86-64 microcode bundles

SYNOPSIS¶

iucode_tool [options] [[-ttype] filename|dirname] ...

DESCRIPTION¶

iucode_tool is an utility that can load Intel® processor microcode data from files in both text and binary microcode bundle formats. It can output a list of the microcodes in these files, merge them, upload them to the kernel (to upgrade the microcode in the system processor cores) or write some of them out to a file in binary format for later use. iucode_tool will load all microcodes in the specified files and directories to memory, in order to process them. Duplicated and outdated microcodes will be discarded. It can read microcode data from standard input (stdin), by specifying a file name of “-” (minus sign). Microcode data files are assumed to be in .dat text format if they have a .dat suffix, and to be in binary format otherwise. Standard input (stdin) is assumed to be in .dat text format. The -t option can be used to change the type of the files specified after it, including for stdin. If a directory is specified, all files whose names do not begin with a dot will be loaded, in unspecified order. Nested directories are skipped. Empty files and directories are ignored, and will be skipped. You can select which microcodes should be written out, listed or uploaded to the kernel using the -S, -s, --date-before and --date-after options. Should none of those options be specified, all microcodes will be selected. You can upload the selected microcodes to the kernel, write them out to a file (in binary format), to a Linux early initramfs archive, to per-processor-signature files in a directory, or to per-microcode files in a directory using the -w, --write-earlyfw, -k, -K, and -W options. For more information about Intel processor microcodes, please read the included documentation and the Intel manuals listed in the SEE ALSO section.

OPTIONS¶

iucode_tool accepts the following options:

-q, --quiet

Inhibit usual output.

-v, --verbose

Print more information. Use more than once for added verbosity.

-h, -?, --help

List all available options and their meanings.

--usage

Show summary of options.

-V, --version

Show version of program.

-t type

Sets the file type of the following files. type can be:

--downgrade

When multiple versions of the microcode for a specific processor are available from different files, keep the one from the file loaded last, regardless of revision levels. Files are always loaded in the order they were specified in the command line. This option has no effect when just one file has been loaded.

--no-downgrade

When multiple versions of the microcode for a specific processor are available from different files, keep the one with the highest revision level. This is the default mode of operation.

--strict-checks

Perform strict checks on the microcode data. It will refuse to load microcodes and microcode data files with unexpected size and metadata. It will also refuse to load microcode entries that have the same metadata, but different payload. This is the default mode of operation.

--no-strict-checks

Perform less strict checks on the microcode data. Use only if you happen to come across a microcode data file that has microcodes with weird sizes or incorrect non-critical metadata (such as invalid dates), which you want to retain. If you just want to skip those, use the --ignore-broken option.

--ignore-broken

Skip broken microcode entries when loading a microcode data file, instead of aborting program execution. If the microcode entry has an unknown format or had its header severely corrupted, all remaining data in the file will be ignored. This option is also useful to process data files with extra padding at the end (the padding will be reported as an invalid microcode entry), as well as to salvage microcodes from an incomplete data file.

--no-ignore-broken

Abort program execution if a broken microcode is found while loading a microcode data file. This is the default mode of operation.

-s ! | [!]signature[,pf_mask]

Select microcodes by the specified signature and processor flags mask (pf_mask). If pf_mask is specified, it will select only microcodes that are suitable for at least one of the processor flag combinations in the mask.

Specify more than once to select more microcodes. This option can be combined with the --scan-system option to select more microcodes. If signature is prefixed with a “!” (exclamation mark), it will unselect microcodes instead. Ordering matters, with later -s options overriding earlier ones.

The special notation -s! (with no signature parameter) instructs iucode_tool to require explicit inclusion of microcode signatures (using the non-negated form of -s, or using --scan-system).

The --scan-system option has precedence, therefore the microcodes it selects cannot be unselected.

-S, --scan-system

Select microcodes by scanning all online processors on this system for their signatures.

This option can be combined with the -s option to select more microcodes.

Should the signature scan fail on all online processors, the program will print a warning to the user and continue as if --scan-system had not been specified. This is a fail-safe condition when iucode_tool is used to install microcode updates for the next boot.

--date-before=YYYY-MM-DD and --date-after=YYYY-MM-DD

Limit the selected microcodes by a date range. The date must be given in ISO format, with four digits for the year and two digits for the month and day and “ -” (minus sign) for the separator. Dates are not range-checked, so you can use --date-after=2000-00-00 to select all microcodes dated since January 1st, 2000.

--loose-date-filtering

When a date range is specified, all revisions of the microcode will be considered for selection (ignoring just the date range, all other filters still apply) should any of the microcode's revisions be within the date range.

--strict-date-filtering

When a date range is specified, select only microcodes which are within the date range. This is the default mode of operation.

-l, --list

List selected microcode signatures.

-L, --list-all

List all microcode signatures while they're being processed.

-k[device], --kernel[=device]

Upload selected microcodes to the kernel. Optionally, the device path can be specified (default: /dev/cpu/microcode). This update method is being deprecated.

-K[directory], --write-firmware[=directory]

Write selected microcodes with the file names expected by the Linux kernel firmware loader. Optionally, the destination directory can be specified (default: /lib/firmware/intel-ucode).

-wfile, --write-to=file

Write selected microcodes to a file in binary format.

--write-earlyfw=file

Write selected microcodes to an early initramfs archive, which should be prepended to the regular initramfs to allow the kernel to update processor microcode very early during system boot.

-Wdirectory, --write-named-to=file

Write selected microcodes to the specified directory, one microcode per file, in binary format. The file names reflect the microcode signature, mask and revision.

--overwrite

Remove the destination file before writing, if it exists and is not a directory. The destination file is not overwritten in-place. Hardlinks will be severed, and any existing access permissions, ACLs and other extended attributes of the old destination file will be lost.

--no-overwrite

Abort if the destination file already exists. This is the default mode of operation. Do note that iucode_tool does not follow non-directory symlinks when writing files.

NOTES¶

iucode_tool reads all data to memory before doing any processing. iucode_tool creates files with permissions 0644 (rw-r--r--), modified by the current umask. iucode_tool's selected microcode listing and microcode output files are sorted by cpu signature, however the ordering inside a group of microcodes that share the same cpu signature is undefined: it is deterministic, but it is sensitive to command line parameters and their ordering, and also depends on the ordering of the individual microcodes inside each loaded data file. When multiple revisions of a microcode are selected, the older ones will be skipped. Only the newest selected revision of a microcode (or the last one in load order when the --downgrade option is active) will be written to a file or uploaded to the kernel. Intel microcode data files, both in binary and text formats, can be concatenated to generate a bigger and still valid microcode data file. iucode_tool does not follow symlinks when writing microcode data files. It will either refuse to write the file and abort (default mode of operation), or (when the --overwrite option is active) it will remove the target symlink or file (and therefore breaking hardlinks) before writing the new file. iucode_tool does follow directory symlinks to locate the directory to write files into.

Linux Notes¶

The cpuid kernel driver is required for the --scan-system functionality to work. Early initramfs support for microcode updates is available since Linux v3.9. Kernels without early initramfs support will just make the microcode file available to the initramfs environment at /kernel/x86/microcode/GenuineIntel.bin. The early initramfs image with microcode update data must be aligned to a 16-byte boundary relative to the start of the initramfs file to work around a bug in some versions of the Linux kernel. Each Intel processor microcode must be uploaded through a single write syscall to /dev/cpu/microcode, but more than one microcode can be uploaded per write syscall. Writing the microcode to the kernel device will update all system processor cores at once. This method is being deprecated and does not work on other system processor types. The old Linux firmware interface for microcode updates needs to be triggered on a per-core basis, by writing the number 1 to /sys/devices/system/cpu/*/microcode/reload. Depending on kernel version, you must either trigger it on every core to avoid a dangerous situation where some cores are using outdated microcode, or the kernel will accept the request only for the boot processor and use it to trigger an update on all system processor cores. Since Linux v3.6, the per-core interface has been replaced with a new interface that explicitly triggers an update for every core at once when the number 1 is written to /sys/devices/system/cpu/microcode/reload. The microcode driver should not be unloaded unless you are sure it is not going to be needed. Depending on kernel version and configuration, the driver needs to be loaded for the kernel to be able to reapply the microcode updates after the system resumes from suspend or hibernation, and also to update any system processor cores that were offline at the time the update was applied.

EXAMPLES¶

Updating files in /lib/firmware/intel-ucode:¶

iucode_tool -K/lib/firmware/intel-ucode /lib/firmware/intel-ucode/* /tmp/file-with-new-microcodes.bin

Processing several compressed files at once:¶

zcat intel-microcode*.dat.gz | iucode_tool -k -

zcat intel-microcode*.bin.gz | iucode_tool -k -tb -

BUGS¶

Microcode with negative revision numbers is not special-cased, and will not be preferred over regular microcode. Files are not replaced atomically: if iucode_tool is interrupted while writing to a file, that file will be corrupted.

SEE ALSO¶

The Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 3A: System Programming Guide, Part 1 (order number 253668), section 9.11.

AUTHOR¶

Henrique de Moraes Holschuh <hmh@hmh.eng.br>