On Thu, Mar 07, 2019 at 11:40:05AM +0100, Paolo Bonzini wrote: > On 07/03/19 07:39, Thomas Huth wrote: > > On 06/03/2019 19.12, Paolo Bonzini wrote: > >> Hi all, > >> > >> lately I have been thinking of converting the QEMU build system to > >> Meson. Meson is a relatively new build system that can replace > >> Autotools or hand-written Makefiles such as QEMU; as a die-hard > >> Autotools fan, I must say that Meson is by far better than anything else > >> that has ever tried to replace Autotools, and actually has the potential > >> to do so. > >> > >> Advantages of Meson that directly matter for QEMU include:[...] > > > > I'm not objecting a new build system per se, but could you elaborate on > > problems of the current QEMU build system that will be fixed by this > > change? > > In order of importance: > > - Make lacks introspection abilities; people want to be able to quickly > say "I don't have this security issue because I didn't compile this > file". Make only gives you the build logs, which may not be easily > accessible to the end user. > > - Makefile.objs unnesting does not apply throughout the tree, for > example it does not apply to tests. We don't apply it there because it > it is hard to extend Makefile.objs to dozens of targets and it would > also be very very slow. The result is lack of homogeneity between > places that use Makefile.objs and places that use Makefile.include. > > - Makefile.objs unnesting is hard to understand---granted, you rarely > have to understand it because it mostly works, but we should consider > whether it is a local optimum. For example, how many people know how to > add a dynamically-loadd module to Makefile.objs?
We have a long standing bug in unnesting which breaks if two dirs have a .c file with the same name and a per-o file library link: https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg02654.html The nesting stuff is insanely clever, but it is also fragile and full of dragons like this one. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
