The 14 firms, listed by Red Hat in a statement on Monday, are Amazon, Arm, Canonical, GitLab, Intel Corporation, Liferay, Linaro, MariaDB, NEC, Pivotal, Royal Philips, SAS, Toyota and VMware.
The Commitment was rolled out initially in November 2017, with Red Hat, IBM, Facebook and Google joining up. In March this year, CA Technologies, Cisco, HPE, Microsoft, SAP, and SUSE joined the group.
Under this Commitment, the companies agree to provide GPL licence violators time to come into compliance. The GPL versions 2 and 2.1 do not offer this time interval but deem someone who has committed a violation to be immediately found not to be in compliance.
Earlier this year, Red Hat announced a change in its licensing terms, saying that in future all company projects that chose to use the GNU General Public Licence version 2 or the Lesser General Public Licence version 2 would have to include language from the GPLv3 that provides violators with time to rectify their offence.
The 24 companies which are now part of the Commitment represent more than 39% of corporate contributions to the Linux kernel, including six of the top 10 contributors.