Re: porting musl to RISCV-64

[Szabolcs Nagy <nsz@port70.net>]

* Gry Gunvor <gry.gunvor@gmail.com> [2016-05-10 23:05:01 -0700]:
> Newlib is small, but I am not interested in multithreading and the
> multithreading/reentrancy support they have built into the library is
> causing me problems.  So I thought I would try musl.
> 

newlib is for baremetal development, you don't
need to use threading with it, but on linux i
think it uses the mostly broken linuxthreads.

musl is a conforming posix libc so it has
complete pthreads support.

> Anyway, suppose I want to port musl to RISCV-64 and cross-compile it.
> MIPS is a RISC architecture that is rather close to RISCV, but your
> MIPS support says 32-bit (and big-endian), so I take it you have some
> dependencies on what used to be called the "machine word size" (RISCV
> is 64-bit, but the RISCV docs still call a 32-bit unit a "word"; ugh;
> so now we need a new word for "word").  Thus I suspect that this is
> going to be non-trival.  How much work is this going to be?  Hints?
> 

musl now has 32bit mips, mips64 and mipsn32 support as well.
these are different abis so they have to be separate ports,
same is true for the riscv targets.

there is a google summer of code project to add riscv support
http://www.openwall.com/lists/musl/2016/04/27/3
i think it is supposed to provide a working port within 1-2
months (?) so if you can wait you don't need to do much work.

> More generally, any comments on what do you recommend as the easiest
> thing to do?  Port musl to RISCV-64?  Use a different libc?  For those
> of you who know newlib, hack newlib to remove reentrancy goop?
> 

i don't know what you are trying to do so it's hard to tell,
if you want a complete userspace on linux then i think a newlib
subset is not enough, but if you want to get some specific
application to run then it might work.