Removing Old 32-Bit ARM Platforms Could Cut About 247,000 Lines From Linux

Arnd Bergmann’s work to remove obsolete 32-bit ARM platforms from Linux could cut roughly a quarter of a million lines from the kernel once the drivers that only those platforms use go too, Phoronix reported.

The platform code itself accounts for about 55,000 lines. Bergmann’s board-remove-7.3 Git branch goes further and clears out the associated drivers: at the time of Phoronix’s report, about 300 patches deleted some 247,000 lines and added about 5,000. For scale, the kernel source tree is close to 41 million lines.

What’s going

The platforms on the list are SA1100, Footbridge, RISCPC, Orion, Dove, MV78xx0, OMAP24xx, i.MX31, i.MX targets without an MMU, LPC18xx, STM32f4/f7/h7 MCUs, Versatile MPS2, AT91 SAMV7, Axxia and legacy PXA board files.

They were marked deprecated in Linux 7.3. In that pull request, Bergmann said the code “does have the tendency of getting in the way of cleanups and new features but has close to zero users.” The deprecations covered 22 of the remaining 28 legacy board files that predate devicetree, mostly for old Intel and Marvell chips; the other six, for TI OMAP1 and Samsung S3C64xx chips, stay because they still have known users. Support for Cortex-M3/M4/M7 and ARM1136r0 cores and the 25 machines built on them was also deprecated, along with be8, be32, OABI and iWMMXt userspace binaries, which Bergmann said are increasingly hard to support with modern toolchains.

Timing

Nothing was removed in 7.3, so remaining users keep the 7.3 LTS kernel for a while. Bergmann has said the removals could land in Linux 7.4 but he leans toward 7.5, to keep dependencies simple, move past this year’s LTS release and give any lingering users more time to make their case, Phoronix reported earlier.

The branch is public for anyone who wants to check which drivers are on the way out.