Arnd Bergmann began his 2025 Linux Plumbers Conference session on the future of 32-bit support in the Linux kernel by saying that it was to be a followup to his September talk on the same topic. The focus this time, though, was on the kernel’s “high memory” abstraction, and when it could be removed. It seems that the kernel community will need to support 32-bit systems for some time yet, even if it might be possible to remove some functionality, including support for large amounts of memory on those systems, more quickly.

The high-memory problem

High memory, he began, is needed to support 32-bit systems with more than 768MB of installed physical memory with the default kernel configuration; it can enable the use of up to 16GB of physical memory. The high-memory abstraction, though, is a maintenance burden and “needs to die”. Interested readers can learn more about high memory, why it is necessary, and how it works in this article.