Date: Tue, 18 Jun 2019 14:19:06 -0700 From: Reinoud Koornstra <reinoudkoornstra@...il.com> To: Rich Felker <dalias@...c.org> Cc: musl@...ts.openwall.com Subject: Re: where to find musl-gcc wrapper script I noticed that the -static gives me some weird stuff. If I use glibc to compile gdb and then rerun the compile command with static I do get to see it's a statically linked binary. It'll end up with warnings, but ... gdb compiles fine with musl as well. So after compiling i see: ELF 32-bit executable, ARM, EABI5 version 1 (SYSV). dynamically linked, interpreter /lib/ld-musl-armhf.so.1 When I add -static to the arm-linux-musleabihf-g++ command it compiles seemingly fine as well. However when i run file again over this I see: ELF 32-bit executable, ARM, EABI5 version 1 (SYSV). dynamically linked, interpreter, /usr/lib/ld.so.1 .... So adding -static didn't seem to have the desired effect, it also all over sudden showed a different interpreter. Any ideas? Thanks, Reinoud. On Tue, Jun 18, 2019 at 11:43 AM Rich Felker <dalias@...c.org> wrote: > > On Tue, Jun 18, 2019 at 11:27:51AM -0700, Reinoud Koornstra wrote: > > On Tue, Jun 18, 2019 at 10:49 AM Rich Felker <dalias@...c.org> wrote: > > > > > > On Mon, Jun 17, 2019 at 08:28:12PM -0700, Reinoud Koornstra wrote: > > > > On Mon, Jun 17, 2019, 7:47 PM Rich Felker <dalias@...c.org> wrote: > > > > > > > > > On Mon, Jun 17, 2019 at 07:30:00PM -0700, Reinoud Koornstra wrote: > > > > > > Ok the wrapper is included in the musl library itself in the obj > > > > > directory. > > > > > > > > > > Yes, or installed in $prefix/bin if you install. If you don't install > > > > > it won't be able to find its spec file. > > > > > > > > > > > c++ isn't supported yet? > > > > > > > > > > Right. Nobody I'm aware of understands the details of this, but > > > > > apparently either GCC's actual C++ headers or its "precompiled header" > > > > > versions of them pull in a bunch of stuff from glibc, and then it > > > > > breaks when you try to reuse them with musl. It's probably not that > > > > > hard to figure out the root cause and maybe even make it work, but > > > > > nobody has done it and interest is low because it's still a big hack > > > > > compared to just building a proper cross toolchain. > > > > > > > > > > > Currently I configure with CC=musl-gcc > > > > > > CFLAGS="-I/home/me/MUSL/include" LDFLAGS="-L/home/me/lib" ./configure > > > > > > the final g++ comand also add -lrt, need more changes for this to work? > > > > > > > > > > If you do that you're compiling against musl's headers but then > > > > > linking against glibc, which is going to make a huge broken mess. > > > > > > > > Yes, I noticed, so how can I force it to link against musl as well? > > > > > > You can't, because things already went wrong as soon as you compiled > > > against glibc's C++ headers using the glibc-based host g++. > > > > > > > > If you need C++, you really should just build a cross toolchain with > > > > > musl-cross-make. It's as simple as clining the mcm repo and running > > > > > "make TARGET=x86_64-linux-musl OUTPUT=/some/dir install" -- it will > > > > > download, check hashes on, and patch all the components you need and > > > > > give you a clean self-contained cross toolchain in the OUTPUT dir. > > > > > > > > > > > > > Also done that, in that case should I just use the compiled gcc as cc? > > > > > > You can pass the resulting x86_64-linux-musl-gcc and > > > x86_64-linux-musl-g++ as CC and CXX, but for software using the > > > standard tuple prefix conventions, you'd tell it you're cross > > > compiling for x86_64-linux-musl (e.g. by passing > > > --host=x86_64-linux-musl to configure) and it would automatically pick > > > them up as long as they're in your PATH (which you probably need to > > > add them to, e.g. PATH=$PATH:/path/to/mcm/output/bin). This is better > > > if the software has reason to need to know it's being cross compiled, > > > or if it uses other utilities like ar, ranlib, direct use of ld, etc. > > > in the build process, since it will pick up the right ones from the > > > cross toolchain. > > > > Ok, this seemed to have worked nicely. Question, it does add -lrt in > > the end, do I need this in musl or is it build in libc? > > Also, is there a way to verify everything linked nicely by the musl-ld? > > You can include -lrt or omit it; it doesn't matter. musl provides > librt purely as an empty static library file to allow link commands > that include it (POSIX specifies that it must be accepted), so it > makes no difference to the output. All functionality is in libc.a/.so. > > Rich
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