FreeBSD, kernel and base, was ported to CHERI, along with PostgreSQL.
> We have adapted a complete C, C++, and assembly-language software stack, including the opensource FreeBSD OS (nearly 800 UNIX programs and more than 200 libraries including OpenSSH, OpenSSL, and bsnmpd) and PostgreSQL database, to employ ubiquitous capability-based pointer and virtual-address protection.
> We have adapted a complete C, C++, and assembly-language software stack, including the opensource FreeBSD OS (nearly 800 UNIX programs and more than 200 libraries including OpenSSH, OpenSSL, and bsnmpd) and PostgreSQL database, to employ ubiquitous capability-based pointer and virtual-address protection.
Most programs didn't require any changes at all. Even most pointer-integer-pointer conversions can be automatically handled by the toolchain and runtime. See https://www.cl.cam.ac.uk/research/security/ctsrd/pdfs/201904...