Intel Linear Address Masking "LAM" Merged Into Linux 6.4

Since 2020 Intel engineers have been working on Linear Address Masking (LAM) as a feature similar to Arm's Top Byte Ignore (TBI) for letting user-space store metadata within some bits of pointers without masking it out before use. This can be of use to virtual machines, profiling / sanitizers / tagging, and other applications. The Intel LAM kernel support has finally been merged with Linux 6.4.

Intel LAM was originally sent in for Linux 6.2 but at that stage last year Linus Torvalds ended up rejecting it after pointing out some issues.

After the code has been improved upon (although Linus Torvalds still not personally liking the feature's name), he has now pulled the enablement code for Linux 6.4.

The LAM support was sent in as part of the x86/mm pull request. Linus Torvalds on Friday went ahead and merged the code. He didn't raise any fundamental objections this time to the code though he did end up writing a mew patch himself to make access_ok() independent of LAM after not being fond of that aspect. So look for Intel LAM now in Linux 6.4.