Linux 5.19 Finally Removes Obsolete x86 a.out Support

Written by Michael Larabel in Linux Kernel on 25 May 2022 at 01:15 PM EDT. 14 Comments
Way back in 2019 the Linux kernel deprecated a.out support given that it was superseded by ELF, which itself has already been supported for over two decades going back to Linux 1.x kernels. With Linux 5.19, the obsolete 32-bit x86 a.out support is finally being removed for good from the kernel.

With the prior kernel cycle (Linux 5.18), a.out support was no longer being built for m68k and Alpha while now for v5.19 it's the milestone of clearing out the x86 a.out code.

Back in March I reported that it was expected with preparing to remove the 32-bit a.out support while it missed v5.18 is ready to go for this new kernel cycle. This executable / object code / shared library file format was used prior to the dominance of ELF but has no real use in the modern world. This is unrelated to many compilers naming executables as "a.out" if no output name is given, as with modern compilers those are still in ELF format rather than the a.out format itself. The x86 a.out support has been deprecated since Linux 5.1 and no one complained about losing support for these old binaries with ELF long being superior and more widely used.

With the x86/cleanups for Linux 5.19 is the removal of the x86 a.out support.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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