Should Linux Drop i486 Support? Linus Torvalds Explains the Rationale

Linus Torvalds supports the idea of dropping Intel i486 (i486) processor support from the Linux kernel.

Ten years after Linux abandoned i386 support, i486 has been the lowest x86 processor supported in the mainline kernel. Recently, Linus suggested that supporting only x86‑32 CPUs with the "cmpxchg8b" instruction—available on Pentium and later CPUs—might be sufficient.

"Maybe we should bite the bullet and say we only support x86‑32 with 'cmpxchg8b' (i.e., Pentium and newer)."

Most, if not all, Linux distributions have enabled X86_PAE, making X86_CMPXCHG64 a basic requirement. Modern distributions rarely target 32‑bit development; Linux dropped i386 support in 2012, and by 2022 it may be time to drop i486 support as well.

A developer once claimed to still have an i486 system with some use, but such users are extremely rare.

Torvalds wrote on the kernel mailing list that continuing to support i486 in the kernel is unnecessary.

"I *really* don't think i486‑class hardware is meaningless. Yes, it exists (Maciej is an example), but from a kernel development perspective, I don't see it as relevant." "At times people treat them as museum pieces; if so, they can run a kernel that fits a museum exhibit. Requiring cmpxchg8b isn't unreasonable to me." "Ancient CPUs should have ancient system architectures."

With Linux 6.1 potentially becoming this year's LTS kernel, there is hope that Linux 6.2 will continue the trend and drop the old i486 architecture support.

The i486 architecture debuted in 1989 and was superseded by Intel's Pentium series in 1993. Intel officially discontinued the 486 in 2007, and it no longer appears in detailed product databases.

Anyone still running such devices should have already moved on, as there is no technical support, no new toolchains, and no developers willing to revisit the platform.

It appears that some chapters of Linux history are destined to become legend.