Hello Keiko,
welcome to the mailing list!
As far as I know, there is nobody using llvm as tool chain for Genode. I do not see any principle show stopper though. So you are welcome to explore this direction. While doing so, you may find the reasoning behind our tool-chain customizations useful, which is given in Section 7.2. "C++ runtime" of the documentation [1].
It is also worth noting that our Rust support uses the official Rust tool chain, which is based on llvm. It produces binaries that work on Genode. You can find the used llvm target configurations at [2].
[1] https://genode.org/documentation/genode-foundations-16-05.pdf [2] https://github.com/genodelabs/genode/tree/master/repos/libports/src/lib/rust...
I wonder if you would accept these changes as a minor fix if I follow the "Contributing to Genode" guideline?
It goes without saying that your fixes are welcome! :-) Would you consider opening corresponding issues at GitHub?
Cheers Norman