m4 was hugely popular in the past, because autotools, automake, flex, bison and
many other things used it. But nowadays it much less popular, and might not even
be installed in the buildroot. (m4 is small, so it doesn't make a big difference.)
(FWIW, Fedora dropped make from the buildroot now,
https://fedoraproject.org/wiki/Changes/Remove_make_from_BuildRoot. I think it's
reasonable to assume that m4 will be dropped at some point too.)
The main reason to drop m4 is that the syntax is not very nice, and we should
minimize the number of different syntaxes that we use. We still have two
(configure_file() with @FOO@ and jinja2 templates with {{foo}} and the
pythonesque conditional expressions), but at least we don't need m4 (with
m4_dnl and `quotes').
m4 was nice in '85, but the syntax feels a bit dated. Since we use python for
meson, let's use a popular python templating engine to replace some m4 usage.
A little nicety is that typos are caught:
FAILED: sysusers.d/systemd-remote.conf
/usr/bin/meson --internal exe --capture sysusers.d/systemd-remote.conf -- /home/zbyszek/src/systemd/tools/meson-render-jinja2.py config.h ../sysusers.d/systemd-remote.conf.j2
Traceback (most recent call last):
File "/home/zbyszek/src/systemd/tools/meson-render-jinja2.py", line 28, in <module>
print(render(sys.argv[2], defines))
File "/home/zbyszek/src/systemd/tools/meson-render-jinja2.py", line 24, in render
return template.render(defines)
File "/usr/lib/python3.9/site-packages/jinja2/environment.py", line 1090, in render
self.environment.handle_exception()
File "/usr/lib/python3.9/site-packages/jinja2/environment.py", line 832, in handle_exception
reraise(*rewrite_traceback_stack(source=source))
File "/usr/lib/python3.9/site-packages/jinja2/_compat.py", line 28, in reraise
raise value.with_traceback(tb)
File "<template>", line 8, in top-level template code
jinja2.exceptions.UndefinedError: 'HAVE_MICROHTTP' is undefined
This checking mirrors what 349cc4a507 did for C defines.
This reverts commit a2031de849.
The patch itself seems OK, but it exposes a bug in lxml or libxml2-2.9.12 which
was just released. This is being resolved in
https://gitlab.gnome.org/GNOME/libxml2/-/issues/255, but it might be while. So
let's revert this for now to unbreak our CI.
Fixes#19601.
I occasionally do 'build/man/man systemd.directives' when working on man pages,
and it's annoying slow. By paralellizing the parsing of xml, we can make it a
bit faster.
This is still rather innefficient. Only the parsing part is serialized, xml is
still produced serially at the end, which is hard to avoid.
$ ninja -C build man/systemd.directives.xml
before:
8.20s user 0.21s system 99% cpu 8.460 total
8.33s user 0.18s system 98% cpu 8.619 total
8.72s user 0.19s system 98% cpu 9.019 total
after:
13.99s user 0.73s system 345% cpu 4.262 total
14.15s user 0.35s system 348% cpu 4.161 total
14.33s user 0.35s system 339% cpu 4.321 total
I.e. it uses almost twice as much cpu, but cuts the wallclock time down (on a
2-core/4-thread cpu) to about half too, which is an overall win if you're just
trying to render the man page.
The change from list and .append() to set and .add() is something that could
have been done before too, but it's noticable now. It cuts down on the
serialization/deserialization time (about .2s).
Add a build script to compile bpf source code. A program in restricted
C is compiled into an object file. Object file is converted to BPF
skeleton [0] header file.
If build with custom meson build rule, the target header will reside in
build/ directory (not in source tree), e.g the path for socket_bind:
`build/src/core/bpf/socket_bind/socket-bind.skel.h`
Script runs the phases:
* clang to generate *.o from restricted C
* llvm-strip to remove useless DWARF info
* bpf skeleton generation with bpftool
These phases are logged to stderr for debug purposes.
To include BTF debug information, -g option is passed to clang.
[0] https://lwn.net/Articles/806911/
When executed in test mode, "OUTDATED" is appropriate. But when executed
to actually update the text, after the tool executes, those pages are the
opposite, not outdated.
668b3a42fe allowed update-dbus-docs.py to start
running on Cent OS 8 (instead of skipping). But subprocess.check_output()'s
text argument didn't exist until Python 3.7 and C8 is still running
Python 3.6. Use universal_newlines instead for backwards compatibility.
The target is update-syscall-tables, so let's call the script
update-syscall-tables.sh to reduce the cognitive overhead when
trying to find the right file.
Upstream uses .text, but this is rather unusual. Let's use .txt as the usual
suffix for text files. This tells various editors and such that the file should
be treated as plain text. I also want to a script to summarize license status,
and having an easy-to-recognize suffix makes this easier.
Even though many of those scripts are very simple, it is easier to include
the header than to try to say whether each of those files is trivial enough
not to require one.
The script is renamed to match.
Now all targets are named uniformly in a tab-completion-friendly fashion, with
the exception of systemd-update-po which is generated by the i18n module
automatically:
$ ninja -C build -t targets | grep update
systemd-update-po: phony
update-syscall-tables: phony
update-syscall-header: phony
update-hwdb: phony
update-hwdb-autosuspend: phony
update-dbus-docs: CUSTOM_COMMAND
update-man-rules: CUSTOM_COMMAND
Very old versions of meson did not include the subdirectory name in the
target name, so we started adding various "top-level" custom targets in
subdirectories. This was nice because the main meson.build file wasn't
as cluttered. But then meson started including the subdir name in the
target name. So let's move the definition to the root so we can have all
targets named uniformly.
