The gcov support added to the kernel in r344487 doesn't work with modules. Everything seems to be working for the kernel itself, but when I try to load a module I get this error:
> sudo kldload fdescfs
kldload: an error occurred while loading module fdescfs. Please check dmesg(8) for more details.
> tail -n2 /var/log/messages
Jul 13 20:14:08 fbsd-head kernel: kldload: fdescfs.ko: lost base for reltab
Jul 13 20:14:08 fbsd-head kernel: linker_load_file: /boot/kernel.old/fdescfs.ko - unsupported file type
I don't observe the kldload failure when I build a GENERIC kernel using the amd64-gcc cross toolchain. I only see it when using the GCOV kernel. If I cd to /usr/src/sys/modules/whatever and build the module there, then I _can_ load it. However, coverage data is not collected.
> sudo kldload /boot/modules/fusefs.ko
> uname -a
FreeBSD fbsd-head.lauralan.noip.me 13.0-CURRENT FreeBSD 13.0-CURRENT r349977 GCOV amd64
> cat sys/amd64/conf/GCOV