reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/commit/?id=babed7b34c5946d07f915c7e4aab26fa2470ff86
        git remote add arnd-playground https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git
        git fetch --no-tags arnd-playground 8250-cleanup
        git checkout babed7b34c5946d07f915c7e4aab26fa2470ff86
        # choose either of the following two methods to reproduce the issue
        # 1. reproduce by kismet
           # install kmax per https://github.com/paulgazz/kmax/blob/master/README.md
           kismet --linux-ksrc=linux --selectees CONFIG_SERIAL_8250_LEGACY_ISA --selectors CONFIG_SERIAL_8250_HP300 -a=m68k
        # 2. reproduce by make
           cd linux
           # download the config file from the "config:" link in the report, and save it as .config
           make ARCH=m68k olddefconfig