Linus Torvalds Slams Intel’s Linear Address Masking (LAM) in Linux 6.2

Linus Torvalds, known for his blunt criticism of hardware vendors, recently attacked Intel’s new Linear Address Masking (LAM) feature, which Intel wants to merge into the Linux 6.2 kernel.

LAM, introduced by Intel in 2020, is a mechanism that uses unused high‑order bits of user‑space addresses as metadata, similar to AMD’s UAI and ARM’s TBI, and is expected to appear in the upcoming Sapphire Rapids CPUs.

Torvalds argued that the proposed implementation is fundamentally broken, poorly named, and adds unnecessary complexity to the kernel’s mm subsystem. In the Linux‑kernel mailing list he wrote that Intel should call the feature “Top‑Bits‑Ignore” (TBI) instead of inventing a new acronym.

He further claimed that the changes to untagged_addr() are destructive and that the LAM code would become a persistent bug, even on x86‑64, because it is not specific to the architecture.

After heated discussion, the LAM patch was removed from the 6.2 merge window. Intel’s engineers plan to rewrite the code and submit a revised version for Linux 6.3, hoping to address Torvalds’ concerns.