Take the 2-minute tour ×
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.. It's 100% free, no registration required.

In the linux kernel, there is a section "Library routines" with a snippet shown below:

Library routines  --->
  <M> CRC-CCITT functions
  <M> CRC ITU-T V.41 functions
  <M> CRC7 functions
  <M> CRC32c (Castagnoli, et al) Cyclic Redundancy-Check
  <M> CRC8 function

I have most of the options compiled in as "module", but these modules never get loaded. I'm curious to know what these modules are used for and in which situation I would need them?

The Kernel Config help is not very illuminating:

This option is provided for the case where no in-kernel-tree
modules require <XYZ> functions, but a module built outside
the kernel tree does. Such modules that use library  <XYZ>
functions require M here.
share|improve this question

1 Answer 1

up vote 4 down vote accepted

CCITT stands for "Comité Consultatif International Téléphonique et Télégraphique" and ITU for "International Telecommunication Union". These modules have to do with (error correction) for telephone-modem connections.

Since even old style high-end modems (to which you would normally communicate via a, real, hardware serial port) do things like CRC themselves, my guess is those modules are for low-end hardware, where a large part of the handling was done by the CPU, so called softmodems

So unless you have, and use, that kind of simple modem hardware, your kernel is unlikely to load those modules.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.