Post Syndicated from original https://lwn.net/Articles/836144/rss

The kmap() interface in the kernel is a bit of a strange beast.
It only exists to overcome the virtual addressing limitations of 32-bit
CPUs, but it affects code across the kernel and has side effects on 64-bit
machines as well. A recent discussion on the handling of preemption within
the kernel identified a number of problems in need of attention, one of which was the kmap()
API. Now, an extension to this API called kmap_local() is
being proposed to address some of the problems; it signals another step in
the kernel community’s slow move away from supporting 32-bit machines as
first-class citizens.