If you're talking about modern BSD licenses, basically there's no difference but the wording. Some older BSD licenses were mildly more restrictive, most notably the ones with the advertising clause that technically conflicts with the GPL.

Someone with mod points, please mod up the parent post. Even if you disagree with it, it's informative about one of the big issues in glibc that musl does differently: musl's snprintf and dprintf, for example, are async-signal-safe. Roland McGrath, who holds claim to being the "inventor" of dprintf and author of the original implementation in glibc, has stated that he intended for the function to be async-signal-safe or at least close to it, and that later introduction of dynamic allocation is a bug (which I later filed as #16060) that glibc should fix.

There is no isinf symbol or reference to one in musl, so I think this is something to do with your toolchain (a BSD-packaged version of LLVM that tries to make itself look like gcc?). Pretty much all of your concerns (including "lack of C++") could be solved by building a toolchain to target musl (note: uClibc and glibc make you do this anyway; musl is fairly unique in providing a way, albeit sometimes clunky, to use the new libc without a new compiler toolchain). If you want to do that or proceed trying to get the wrapper to work on your system, you'll find people who can help in Freenode #musl or on the mailing list. On the other hand I understand if you don't want to go to the trouble, but keep in mind you're using a non-native setup that's probably never been tested.

The problem appears to be that "x86_64" is identified by your compiler as "amd64" in the machine tuple. This is easily fixed by adding --target=x86_64 (the name musl knows it by) on the configure command line. I don't see any reason we can't add "amd64" to the detection logic in configure too, so this should work better for you in a future release.

BTW, in case anyone thinks I'm making up the thing about intentionally linking to ancient glibc, see this: http://www.crankuptheamps.com/...

There is a way to upgrade glibc atomically, but it's a big hack, and even still it doesn't achieve the goal. The way it would work is to have /lib be a symlink to a versioned directory, and atomically replace (via rename()) the symlink with a symlink to the new directory. However, even if the replacement is made atomically, you still have the situation that the dynamic linker can load libc.so before the replacement is made and libpthread.so after it's made, resulting in mismatching versions.

I've submitted at least two bugfix patches to glibc where the diff was 100% "-" lines for things Drepper added. I believe they were all eventually committed. And thankfully this is the one type of glibc patch submission that doesn't require having a copyright assignment on file with the FSF. ;-)

It doesn't mean you can't use gdb, just that libc itself does not try to double as a debugging tool. This is actually a security consideration. For example, glibc prints debugging information if it detects corruption in malloc. But if there's already memory corruption, you have to assume the whole program state is inconsistent; the corruption may be intentional due to the actions of an attacker, and various function pointers, etc. may have been overwritten. Continuing execution, even to print debug output, risks expanding the attacker's opportunity to take control of the program.

FWIW, musl does detect heap corruption. The difference is that it immediately executes an instruction that will crash the program rather than trying to continue execution, make additional function calls that go though indirection (the PLT) and access complex data structures, etc.

If you don't want to switch, that's fine. You're still getting the benefits of musl, because competition has driven the glibc developers to fix, or at least study how to fix, a number of longstanding bugs in glibc.

The main effect of glibc being LGPL is not that companies don't use it, rather it's that nobody making non-free software is willing to static-link it, so you end up with versioning hell. glibc partially solves this problem with symbol versioning, but the solution actually makes the problem worse in other cases: for example, in order to provide a binary that runs on systems with older glibc, people making binaries intentionally link against an older glibc, using the outdated/bug-compatible symbol versions instead of the up-to-date ones.

Of course if your goal is to make sure non-free software is always breaking and giving people problems, that's a potential benefit of the LGPL.

With musl, all you have to do to make a binary that works with older versions of the shared libc is avoid using functionality that was introduced in later versions. Or you can just static link and have it work everywhere.

Unlike some projects, we fully disclose bugs that might be relevant to security. In this instance, the bug could only be triggered by explicitly requesting sufficiently many decimal places (16445 for ld80) and printing a denormal long double with the lowest bit set, as in:

printf("%.16445Lf", 0x1p-16445);

In addition, even when triggered, it only wrote past the end of the buffer by one slot, and we were unable to get it to overwrite anything important like a return address (of course, what it overwrites depends on the compiler, so in principle it could).

putw is a nonstandard functions and used by basically nothing, so a simple, obviously does-what-the-man-page-says solution in terms of another well-tested function is preferable to repeating the locking, buffer manipulation, etc. logic in a place that's unlikely to ever get tested.

At the time the comparison was made, glibc was essentially unmaintained and Debian-based distributions were using the eglibc fork. Now that glibc is under new leadership, eglibc is being discontinued and the important changes have been merged back to glibc upstream. So when I update the chart's quantitative comparisons, it will be for glibc rather than eglibc. The main things that will change when I do are significant increases in size (especially since I seem to have under-measured eglibc's totals) and possibly some improvements in performance. In terms of all the other qualitative comparisons, glibc remains about the same place it was before.

We have people working on aarch64, someone interested in doing a sparc port, and interest from the OpenRISC folks in musl too (and I've offered to help them with a port). There's also someone who wants to port to LM32-mmu (which, as I understand it, doesn't have any userspace infrastructure yet and only a very experimental kernel port).

Yes. These days glibc seems to have "un-deprecated" static linking (they're accepting bug reports for problems that only affect static linking), but it's still something of a second-class citizen. I believe there's still a good deal of pthread breakage, and no attention to making the size of static binaries acceptable.

In musl, I've made efficient and bug-free static linking a priority from the beginning. The empty program isn't quite as small as some of our extreme anti-bloat userbase would like (it's around 1.8k now), but it's still very low compared to anything except dietlibc (which has a number of issues). More interestingly, we can do a static-linked multi-threaded "hello world" in under 4k.

Some figures can be seen in the libc comparison I did back when musl was first released.