FreeBSD has used ELF binaries/libraries for decades, but still has support for legacy a.out binaries. Portions of this have been retired over time, and I propose removing the remaining pieces before FreeBSD 13. I'm not proposing making any change to kernel a.out support, but users needing userland a.out tools would have to install them from old FreeBSD releases. I have opened the following reviews for three tools that still support a.out: D27478 ldd: Retire a.out support D27480 gprof: Retire a.out support D27481 ldconfig: Retire a.out support If there are no objections I plan to commit these changes before the end of the month, along with small changes to the mtree file (removing aout directories) etc.