Linux Preparing To Finally Remove Support For The a.out Format

Written by Michael Larabel in Linux Kernel on 13 January 2022 at 03:00 PM EST. 46 Comments
Back in 2019 the Linux kernel deprecated a.out support for that file format used several decades ago before ELF tookover. Now in 2022 it looks like that a.out code will be removed from the kernel.

Linux relied on the a.out format until v1.2 in the mid-90's when ELF became the popular format for binaries. While the a.out format hasn't been widely used on Linux in many years, it took until 2019 for the support to be deprecated for running a.out binaries on x86 32-bit. Compilers and other toolchain components have moved on from the a.out file format for years.

Borislav Petkov today proposed the patch removing the a.out support from the kernel.

The other upstream developers to respond so far have all been in favor of clearing out this deprecated a.out support. There is also the possibility some old system calls and other unused kernel code might get cleaned out too in the process. This removal patch hasn't been submitted for the ongoing v5.17 merge window, but we'll see if it still tries to make it in otherwise is pushed off until v5.18, but in any case it looks like this year will be the year the Linux kernel retires a.out support.
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