Linux Plumbers Conference 2021

Enable intel LAM in linux

21 Sept 2021, 09:15

30m

GNU Tools track/Virtual-Room (LPC Virtual)

GNU Tools Track GNU Tools Track

Speaker

H.J. Lu (Intel)

Description

Intel LAM (Linear Address Masking) Extension allows software to locate metadata in data pointers and dereference them without needing to mask the metadata bits. It supports:

• LAM_U48: Activate LAM for user data pointers and use of bits 62:48 as masked metadata.
• LAM_U57: Activate LAM for user data pointers and use of bits 62:57 as masked metadata.

I am presenting a proposal to enable Intel LAM in Linux:

1. Only LAM enabled Linux on LAM processors can provide LAM features.
2. Every piece of OS must be LAM enabled, starting from kernel, toolchain, libraries, …
3. A binary is LAM enabled only if all its components are LAM enabled.
4. LAM enabled OS is backward compatible. The same LAM-enabled OS binary can run on LAM and legacy processors.
5. Provide LAM features only on LAM processors.
6. Minimum performance loss on legacy processors.

Presentation materials

LAM-LPC-2021.pdf