Quoting Ilia Mirkin (2017-03-16 14:32:09) > On Thu, Mar 16, 2017 at 5:25 PM, Dylan Baker <dylan@xxxxxxxxxxxxx> wrote: > > Why bother, and why would we want this? │~ > > > > First it's written in python, which means the potential developer base > > is massive. And it provides a recursive view for humans, but a > > non-recursive view for the system. This is the best of both worlds, > > humans can organize the build system in a way that makes sense, and the > > machine gets a non-recursive build system. It also uses ninja rather > > than make, and ninja is faster than make inherently. Meson is also a > > simpler syntax than autotools or cmake it's not Turing Complete by > > design nor does it expose python, again, by design. This allows meson > > itself to be reimplemented in a another language if python becomes a > > dead-end or a bottle-neck. It also makes it much easier to understand > > what the build system is doing. > > > > What's different about using meson? > > > > Well, apart from a faster builds and less magic in the build system? The > > configure flags are different, it uses -D<opt>=<value> more like cmake > > than the --enable or --with flags of autotools, although oddly it uses > > --prefix and friends when calling meson, but not with mesonconf, there's > > a bug opened on this. Meson also doesn't support in-tree builds at all; > > all builds are done out of tree. It also doesn't provide a "make dist" > > target, fortunately there's this awesome tool called git, and it > > provides a "git archive" command that does much the same thing. Did I > > mention it's fast? > > > > Here are the performance numbers I see on a 2 core 4 thread SKL, without > > initial configuration, and building out of tree (using zsh): > > > > For meson the command line is: > > time (meson build -Dmanpages=true && ninja -C build) > > > > For autotools the command line is: > > time (mdkir build && cd build && ../autotools && make -j5 -l4)<Paste> > > Probably mkdir... derp, yeah. > > > > > meson (cold ccache): 13.37s user 1.74s system 255% cpu 5.907 total > > autotools (cold ccache): 26.50s user 1.71s system 129% cpu 21.835 total > > meson (hot ccache): 2.13s user 0.39s system 154% cpu 1.633 total > > autotools (hot ccache): 13.93s user 0.73s system 102% cpu 14.259 total > > > > That's ~4x faster for a cold build and ~10x faster for a hot build. > > > > For a make clean && make style build with a hot cache: > > meson: 4.64s user 0.33s system 334% cpu 1.486 total > > autotools: 7.93s user 0.32s system 167% cpu 4.920 total > > > > Why bother with libdrm? > > > > It's a simple build system, that could be completely (or mostly > > completely) be ported in a very short time, and could serve as a tech > > demo for the advantages of using meson to garner feedback for embarking > > on a larger project, like mesa (which is what I'm planning to work on > > next). > > > > tl;dr > > > > I wrote this as practice for porting Mesa, and figured I might as well > > send it out since I wrote it. > > > > It is very likely that neither of these large patches will show up on the > > mailing list, but this is available at my github: > > https://github.com/dcbaker/libdrm wip/meson > > I haven't looked at meson or your patches in detail, but autotools > supports 2 very important use-cases very well: > > 1. ./configure --help > 2. Cross-compilation with minimal requirement from the project being built > > Can you comment on how these are handled in meson? > > Cheers, > > -ilia 1. mesonconf <builddir> provides much the same thing. You can also read the meson_options.txt file, which is generally pretty short. I haven't added descriptions to the options in this patch. 2. you write a small ini style configuration file, something like: [binaries] c = '/usr/bin/aarch64-linux-gnu-gc' ar = '/usr/bin/aarch64-linux-gnu-gcc-ar' strip = '/usr/bin/aarch64-linux-gnu-strip' pkg-config = '/usr/bin/aarch64-linux-gnu-pkgconfig' Then you just configure with: meson build --cross-file cross_file.txt then just ninja like normal There's a more detailed walkthrough here: https://github.com/mesonbuild/meson/wiki/Cross-compilation I was able to cross compile the arm libraries for aarch64 using basically the above configuration (I had to write a wrapper script for pkg-config to set a couple of environment variables and install and archlinux aarach64 chroot, because arch), of course, I don't have access to any arm machines that I could test with. Dylan
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