Failed to invoke compiler in order to build my own code targeting RISC-V purecap on cheriBSD about cheribuild

[jrtc27]

All you need is to point --sysroot at the CheriBSD rootfs directory, i.e. ~/cheri/output/rootfs-riscv64-purecap (~/cheri/output/sdk/sysroot-riscv64-purecap should also work, but it's not what cheribuild tends to use) and -B at ~/cheri/output/sdk/bin, plus any other compiler flags needed to set the triple, architecture, ABI, etc. For example, a minimal correct use would be:

-target riscv64-unknown-freebsd14 --sysroot=$HOME/cheri/output/rootfs-riscv64-purecap -B$HOME/cheri/output/sdk/bin -march=rv64imafdcxcheri -mabi=l64pc128d -mno-relax

~/cheri/output/sdk/utils/cheribsd-riscv64-purecap-clang exists as a convenient wrapper for users to use rather than having to specify those command-line arguments manually (it automatically picks up the set of arguments in ~/cheri/output/sdk/bin/cheribsd-riscv64-purecap.cfg, which you will note is the same as I gave above), though that is intended for users, not machines, to use, i.e. it is not guaranteed to be a stable interface (and hence why it's in utils/ not bin/).

• I tried installing the cheribsd-sdk-native target
  But GDB failed to configure, complaining of missing GMP

Give cheribsd-sdk-native is not a thing that exists, I don't know if this was you trying to build gdb-native or cross-compile GDB for RISC-V. For the former it should pick up gmp from the system, but I guess there's a chance it's broken. gmp-native does exist as a target you can build for that though. If you're cross-compiling then you will of course need a cross-compiled gmp, for which you can use gmp-<target> to match gdb-<target>.