statically link everything but libc

[tamird]

Right now, we are statically linking everything, including libc. This forces us to use musl, because statically linking glibc is insane.

We would like to statically link everything but libc, so that we aren't forced to use such an exotic configuration. This may require us to rethink our current collection of c-* repositories so that we can use upstream build systems to build static binaries which we link against, while letting the go tool dynamically link everything else (which we hope is just libc).

[petermattis]

Why do you think the c-* repositories are related to this? Those repositories result in the generation of static libs.

[tamird]

Not so; static libs are only created if the top level cockroach build is static.

EDIT: I only verified this with c-rocksdb, but I don't see why it would different for the other repos.

[petermattis]

Eh, c-rocksdb is not linked dynamically into my cockroach binaries on Mac OS X. Does this differ on Linux?

[mberhault]

nope:

$ ldd cockroach 
    linux-vdso.so.1 =>  (0x00007fff7654d000)
    librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f3647c1d000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f36479ff000)
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f36476fb000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f36473f5000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f36471df000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3646e1a000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f3647e25000)

where cockroach is from a plain make build

[tamird]

I guess I'm fuzzy on the semantics; I expect that libstdc++ is dynamically linked into cockroach as a result of rocksdb's inclusion (and how it was built), but perhaps that is incorrect.

[petermattis]

The decision to link libstdc++ statically or dynamically is made when the final cockroach binary is linked and is purely determine by the presence or absence of the -static flag being passed to the external linker (e.g. clang++ or g++). I'm about 99% certain that the c-* repositories do not affect this.

[petermattis]

My readings on the internet suggest that glibc = {librt,libpthread,libm,libc} and that all of those libraries should be dynamically linked. linux-vdso.so.1 (virtual dynamic shared object) comes from the kernel. And ld-linux-x86-64.so is the dynamic loader and is required by any program that is linked against shared libraries. That leaves libstdc++ and libgcc that we would like to link statically. Luckily, there is a flag for that (actually 2 flags): -static-libgcc and -static-libstdc++. I suggest we replace usage of -static with those two flags.