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Date: Tue, 4 Dec 2012 15:01:22 -0800
From: Isaac Dunham <idunham@...abit.com>
To: musl@...ts.openwall.com
Subject: Re: Summary of 1.0 marketing plan/scheme/nefarious plot from
 IRC.

On Tue, 4 Dec 2012 16:45:22 -0500
Rich Felker <dalias@...ifal.cx> wrote:

> > The "what are musl's dependencies" faq entry is a mix of bullet
> > points and non-bullet point material that doesn't just clarify the
> > bullet points. It doesn't mention what "make" you need (posix-2008
> > compliance should be enough?) and the shell is implicit (does _not_
> > need bash, posix-2008 again good enough?). Did we actually test
> > Linux 2.6.0?
> 
> Make needs to be GNU make or compatible. Writing makefiles for POSIX
> make is an exercise in wasting maintenance time; there's no way to
> write general or wildcard based rules. As far as I know, it should
> work even with ancient versions of GNU make (pre-GPL3), and would
> probably work with a minimal clone of GNU make (but GNU make itself is
> already very light and portable).

I've used GNU make 3.80, which is the earliest one is _likely_ to encounter (except on distros from last century).  Debian Squeeze still uses 3.81, which is pre-GPL3.


> Shell is not really required at all since you can write your own
> config.mak based on the sample one. Configure is intended to require
> just POSIX sh, not anything from bash; I've never even used it with
> bash myself.

configure works with Busybox and Debian ash, all 3 ksh variants (PD/MirBSD and ksh93), bash... basically every POSIX-style shell except posh, which apparently doesn't support one of the signals we trap. (If I can figure out which one, I'll report it as a bug: posh is supposed to be "Debian Policy" conformant, which is a minimally extended superset of POSIX.)

> >   - c99 compiler with support for gcc-style assembly language. 

Also needs weak symbols. 
In real life this works out to "gcc, clang, or pcc"; there are unidentified issues with Open64, icc might or might not work, and same for Path64 and Sun Studio for Linux.

> > It would be nice if there was some kind of "musl manual". If you
> > want to write a program against the musl libc, what does it provide?
> > (HTML is fine, man page format is kinda archaic these days. This is
> > mostly posix, but not entirely.)

For some folks, but not all.
(I prefer local documentation that can be viewed without a web-browser...)

> Yes, this would be covered in the proposed manual, an outline for
> which I posted to this list a couple weeks back. Right now I'm leaning
> towards having it be my main project between the last 0.9.x release
> and 1.0, to have a major addition for 1.0 (the manual) without the
> risk of regressions from major code changes.
> 
> > If we're not up to writing something, w link to the POSIX spec with
> > the list of functions we've implemented, plus the man7 pages on the
> > linux variations thereof (and system calls) and maybe the Linux
> > Standard Base sort of collectively covers it.
> 
> Basically, my idea is that the manual will "defer to POSIX and ISO C"
> on functions specified by them, with specific notes on extended
> behavior in these functions beyond what the standards require. For
> nonstandard functions, early versions of the manual will probably
> provide a list of what's provided with notes wherever they differ
> significantly from the GNU or BSD functions they're modelled on. Later
> we could expand this documentation to actually cite the relevant BSD
> or Linux man pages.

I still think that documenting what functions we support should be mainly done in the linux-manpages project, which has fairly good coverage and notes libc differences.

> In addition to this, certain functions in the standards have
> implementation-defined behaviors, which means an implementation is
> required to document what behavior it provides. One thing we should
> definitely document is iconv and locale behavior. Compiling a complete
Speaking of which, will musl support the "ASCII" and "" aliases for the C locale, or is that just bloat?  (iirc, these were the issues with R that made libiconv necessary)
> list of the implementation-defined behavior musl needs to document
> would be a good project someone could help out with between now and
> 1.0.
<snip>
> > Dynamic vs static linking, "what is a dynamic linker and wazzit
> > _do_". Something on the whole "how to tell if your binary is built
> > against musl or some other libc, how to tell if it's statically or
> > dynamically linked" (fun with ldd and readelf -a), long ago I wrote
> > an intro to cross compiling if that's worth linking to... Stuff.
> 
> Yes, the "how to tell what libc a binary is linked against?" is
> actually a really good FAQ topic (a question that really arises
> frequently).

I use "strings $BINARY | grep ld.*so"; this lets me see the libc required to run it (or if it's static) as well as arch.

-- 
Isaac Dunham <idunham@...abit.com>

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