IUCODE_TOOL(8) System Manager's Manual IUCODE_TOOL(8)
NAME
iucode_tool - Tool to manipulate Intel(R) IA32/X86_64 microcode bundles
SYNOPSIS
iucode_tool [options] [[-ttype] filename|dirname] ...
DESCRIPTION
iucode_tool is an utility that can load Intel(R) 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 pro-
cessor 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 Duplicated and outdated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, includ-
ing 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.
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) or to per-processor-signature files in a
directory using the -w, -k, and -K 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:
b binary format. This is the same format used by the kernel driver and the BIOS/EFI, which is described in detail by the Intel
64 and IA-32 Architectures Software Developer's Manual, Volume 3A, section 9.11.
d Intel microcode .dat text format. This is the format normally used by Intel to distribute microcode data files.
a (default) iucode_tool will use the filename suffix to select the file type: .dat text format for files that have a .dat suf-
fix, and binary type otherwise. Note that for stdin, .dat text format is assumed.
--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. 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 inside, or to load microcodes from a truncated microcode data file (in which case you will also need the --ignore-
broken option).
--ignore-broken
Skip broken microcode entries during load, instead of aborting execution.
--no-ignore-broken
Abort program execution if a broken microcode is found during load. This is the default mode of operation.
-s [!]signature[,pf_mask]
Select microcodes by the specificed 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 -S option to select more microcodes. If
signature is prefixed with a !, it will unselect microcodes instead. Ordering matters, with later -s options overriding earlier
ones.
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 scan fail, the program will print a warning to the user and continue as if --scan-system had not been specified.
--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 - 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.
-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 filenames 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.
--overwrite
Remove the destination file before writing. Without this option, iucode_tool will abort if the file already exists. Do note that
it will remove symlinks instead of following them.
--no-overwrite
Abort if the destination file already exists. This is the default mode of operation. Do note that iucode_tool does not follow sym-
links when writing files.
NOTES
iucode_tool reads all data to memory before doing any processing.
The microcode data is sorted by cpu signature. Older revisions are removed (either based on revision level or load order, depending on the
--downgrade option) before the data is 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 (--write-to and --write-firmware options). It will either refuse to
write the file and abort (default mode of operation), or remove the symlink before writing (when the --overwrite option is active). It
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.
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. The driver needs to be loaded in order for
the kernel to reapply the microcode updates after the system resumes from suspend or hibernation, and also to update any system processor
cores that were off-line 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
iucode_tool will waste space when writing microcodes with extended signatures (one copy per signature).
The extended signature code is completely untested, and likely buggy. Intel so far has never distributed microcode data files using the
extended signatures.
Microcode with negative revision numbers is not special-cased, and will not be preferred over regular microcode.
SEE ALSO
The Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 3A: System Programming Guide, Part 1 (order number 253668), sec-
tion 9.11.
AUTHOR
Henrique de Moraes Holschuh <hmh@hmh.eng.br>
IUCODE_TOOL 0.8.3 July 28, 2012 IUCODE_TOOL(8)