On Thu, 12.06.14 18:04, Luis R. Rodriguez (mcg...@do-not-panic.com) wrote: > Hey folks, > > so I've been working on getting systemd support on xen for a bit now > and thanks to the last suggestion about the launcher here on > systemd-devel I think we're on the final stretch now. I'll be > submitting a v6 PATCH series shortly which I think should be the last > if not close to the last set we need. It turns out though that I ran > into quite a few issues though, what I consider corner cases with > systemd, and in order to help I've tried to put together a simple > package example source code which exemplifies the complexities I found > but more importantly provide the resolutions to those issues. At the > same time xen also is a good example of a complex piece of software > with multiple OS requirements and on the Linux font you may or may not > want systemd, it also happened to use autoconf, but not automake, and > in one iteration of patches I even worked on systemd support with the > dynamic link loader (dlopen() and dlsym()). Adding proper support for > systemd into xen turned out to be a bit of a mini project. In order to > try to help other though I've generalized as much as I can the > autotools functionality I wrote given I was unable to find a library > to easily add systemd. I'd like your review of this piece of code and > wanted to see if perhaps at least the LGPL m4 libraries might be > welcomed. > > * src/m4/systemd.m4 > > - AX_ENABLE_SYSTEMD(): enables systemd by default and requires an > explicit --disable-systemd option flag to configure if you want to > disable systemd support. > > - AX_ALLOW_SYSTEMD(): systemd will be disabled by default and requires > you to run configure with --enable-systemd to look for and enable > systemd > > - AX_AVAILABLE_SYSTEMD(): systemd will be disabled by default but if your > build system is detected to have systemd build libraries it will be > enabled. You can always force disable with --disable-systemd > > - If you want to use the dynamic link loader you should use > AX_AVAILABLE_SYSTEMD() but must then ensure to use -rdynamic -ldl > when linking, if using automake autotools will deal with this for you, > otherwise you must ensure this is in place on your Makefile.
Hmm, so, I don't think systemd should really be treated differently from other pkg-config-enabled modules. What precisely does this add that pkg-config doesn't support? And wouldn't it be possible to improve pkg-config upstream instead? I don't think we want to support the dlsym() stuff in systemd directly. I mean, if people want to do things like that, that's fine, but I really doubt we should encourage that from upstream. Also note that pretty much any Linux distributions (modulo Gentoo/Slackware) uses systemd already or announced plans to do so, I am not sure it's worth really investing so much time in making systemd optional beyond the usual what pkg-config supports. > Lastly -- I was curious if anyone has looked into writing Coccinelle > SmPL grammar rules to convert legacy init systems with systemd > support. I suspect most unix daemons are rather simple and SmPL rules > might be able to transform quite a bit of them. I don't expect > Coccinelle might be able to catch the crazy daemons with corner cases > as with xen, but you never know, coccinelle is always surprising me > with its capabilities. Note that distribuitions like Fedora have already pretty much converted all their daemons (with exceptions), so I figure this in many ways is too late... Thanks, Lennart -- Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
