Date: Wed, 11 May 2016 09:40:42 -0700 From: Gry Gunvor <gry.gunvor@...il.com> To: musl@...ts.openwall.com Subject: Re: porting musl to RISCV-64 Here's another way to put my question: I've already written my own ghetto riscv-64 libc for synchronous programming (no threads, signals) by writing my own version of what you call syscall_arch.h. Therefore, how hard would it be to factor musl so that syscall_arch.h was all I was depending on that is arch dependent? It seems that should get me a lot of what libc provides. I would want that if I attempt to compile a program that does more than that, say, attempts to use threads/signals/something-weird that I just get a compile-time error. Here's a naive plan: * grep for the inclusion of the other header files in arch other than syscall_arch.h; * for .c files, comment them out in the makefile; * for .h files, insert an #error directive. What will go wrong? Gry On Wed, May 11, 2016 at 9:32 AM, Gry Gunvor <gry.gunvor@...il.com> wrote: > On Wed, May 11, 2016 at 4:25 AM, Szabolcs Nagy <nsz@...t70.net> wrote: > >> newlib is for baremetal development, you don't >> need to use threading with it > > It's attempt at reentrancy support is causing me problems. > >> 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. > > Your documentation does not seem to mention the MIPS64 port, but now > that I look in arch, I see the directory for it. > >> 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. > > Suppose I can't wait and I attempt this myself. Right now I'm just > trying to get a generic libc working. I do not want to handle > multi-threading or signals. What can I omit? Are the > non-portabilities isolated in arch/ ? That is, is there much more to > it than cloning the arch/mips64 directory and hacking on it? > > atomic_arch.h: I think I can make all of these functions empty as I am > not going to be using multi-threading, right? > > crt_arch.h: program startup; what is this doing in a libc > implementation? doesn't the compiler handle this? > > ksigaction.h: sorry, I'm not a hardware person; I suppose different > hardware has a different default layout for a signal object? so this > is not a thing determined by kernel software? I don't care to handle > signals right now anyway. > > pthread_arch.h: again, I think I can make all of these functions empty > as I am not going to be using multi-threading. > > reloc.h: I can't figure out what this is. > > syscall_arch.h: I've already written this for RISCV-64 (and so have > the RISCV people). > > bits: to what extent is this MIPS64-specific? since there is *no* > inline assembly, how come arch/generic/ doesn't do here? > > Gry
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