I've recently started working on compiling UML with LLVM: the goal is to
produce a bitcode version of vmlinux.
With some tweaks to the build process, I can use:
make ARCH=um CROSS_COMPILE=llvm- CFLAGS="-emit-llvm"
to produce vmlinux bitcode.
The question is with respect linker script support. Since llvm-ld does not
support linker scripts--please correct me if I'm wrong--it's clear that some
work is necessary to get things running.
There was a thread on the mailing list last September about this question: