---
name: "hwloc-gather-cpuid"
section: "1"
platform: "linux"
package: "hwloc"
version: "2.15.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/hwloc-gather-cpuid"
---

# hwloc-gather-cpuid(1)

Dumps the relevant x86 cpuid values for later (possibly offline) usage

## NAME

hwloc-gather-cpuid - Dumps the relevant x86 cpuid values for later (possibly offline) usage

## SYNOPSIS

**hwloc-gather-cpuid \[*options*\] \[*\<outdir\>*\]**

## OPTIONS

- **-c \<idx\>**

  **Only gather cpuid values for logical processor whose OS/physical index** **is \<idx\>.**

- **-q** **--quiet** **-s** **--silent**

  Do not show verbose messages.

- **--version**

  Report version and exit.

- **-h** **--help**

  Display help message and exit.

## DESCRIPTION

**hwloc-gather-cpuid** dumps all the relevant x86 cpuid values into subdirectory *cpuid* of current directory, or in **\<outdir\>** if specified.

These files can be used later to explore the machine topology offline, for instance by setting the environment variable *HWLOC\_CPUID\_PATH* to the directory containing all output files, and by forcing the x86 backend with *HWLOC\_COMPONENTS=x86,stop*.

The directory contents may also be submitted to hwloc developers to debug issues remotely.

If **-** is used as \<outdir\>, the output is dumped to the standard output, but a unique logical processor must have been given with **-c**.

**hwloc-gather-cpuid** is a x86 specific tool, it cannot be used on other platforms.

**NOTE:** **hwloc-gather-cpuid** gathers many hardware details about the platform. Output files should not be posted on public lists or websites unless it is clear that they contain no sensitive information.

**NOTE:** The output of **hwloc-gather-cpuid** is included in the tarball saved by **hwloc-gather-topology** on Linux/x86.

**NOTE:** It is highly recommended that you read the [hwloc(7)](/hwloc/7.md) overview page before reading this man page.

## EXAMPLES

To store cpuid information of all logical processors of the current machine:

        $ hwloc-gather-cpuid\
         Gathering in directory ./cpuid ...\
         Gathering CPUID of PU P#0 in path ./cpuid/pu0 ...\
         Gathering CPUID of PU P#1 in path ./cpuid/pu1 ...\
         Gathering CPUID of PU P#2 in path ./cpuid/pu2 ...\
         Gathering CPUID of PU P#3 in path ./cpuid/pu3 ...\
         Summary written to ./cpuid/hwloc-cpuid-info

## RETURN VALUE

Upon successful execution, **hwloc-gather-cpuid** will exit with the code 0.

**hwloc-gather-cpuid** will return nonzero exit status if any kind of error occurs, such as (but not limited to) failure to create the output files.

## SEE ALSO

[hwloc(7)](/hwloc/7.md), [hwloc-gather-topology(1)](/hwloc-gather-topology/1.md), [lstopo(1)](/lstopo/1.md)