Bare metal support

[Stat_headcrabed]

Chris, could you test this?

Does the JH7110 Support RISC-V Extension D?

That was a really interesting question. If you see page 137 of the SiFive U74-MC Core Complex Manual, the mimpid CSR has this information. However looking through the kernel, OpenSBI, and U-boot, surprisingly neither OpenSBI nor the Linux prints this (though they have access to it). U-boot appears to be the only one exposing this via the sbi command, but lo and behold, the U-boot that StarFive ships doesn’t appear to have this enabled. TL;DR: the easiest way to read mimpid currently appear t…