It should make it easier to figure out what exactly services do there.
For example, with SYSTEMD_LOG_LEVEL=debug userdbd (v249) prints
```
varlink-5: New incoming message: {"method":"io.systemd.UserDatabase.GetUserRecord","parameters":{}}
```
before it crashes and systemd-resolved prints
```
varlink-21: New incoming message: {"method":"io.systemd.Resolve.ResolveAddress","parameters":{"address":[127,0,0,1],"flags":0,"ifindex":1000000,"family":0}}
```
and those messages are helpful (especially when scripts causing them
aren't clever enough to keep track of random stuff they send to systemd
:-))
If we assign our own test runner, passing arguments stops working
as unittest won't instantiate its own test runner after it parses
the arguments from sys.argv.
Consequence is that the tests will write to stderr now instead of
stdout since it doesn't seem possible to configure the stream that
unittest.main() will instantiate its test runner with so it'll
default to sys.stderr.
otherwise units using `DynamicUser=yes` won't be able to write the
coverage stats (currently affecting TEST-20-MAINPIDGAMES).
`DynamicUser=yes` implies `ProtectSystem=strict` and
`ProtectHome=read-only` and can't be overridden hence we need to
utilize `ReadWritePaths=` to work around that.
If the test logs contain lines like:
```
...systemd-resolved[735885]: profiling:/systemd-meson-build/src/shared/libsystemd-shared-250.a.p/base-filesystem.c.gcda:Cannot open
```
it means we're possibly missing some coverage since gcov can't write the stats,
usually due to the sandbox being too restrictive (e.g. ProtectSystem=yes,
ProtectHome=yes) or the $BUILD_DIR being inaccessible to non-root users.
Every time I need it I have to first relearn autopkgtest and find where
all the necessary stuff lives, so let's document it somewhere close to
systemd for (at least) future me.
In cbcdcaaa0e ("Add support for conditions on the machines firmware")
a new Firmware= directive was added for .netdev and .network files.
While it was also documented to work on .link files, in actual fact the
support was missing. Add that one extra line to make it work, and also
update the fuzzer directives.
Add the "Isolated" parameter in the *.network file, e.g.,
[Bridge]
Isolated=true|false
When the Isolated parameter is true, traffic coming out of this port
will only be forward to other ports whose Isolated parameter is false.
When Isolated is not specified, the port uses the kernel default
setting (false).
The "Isolated" parameter was introduced in Linux 4.19.
See man bridge(8) for more details.
But even though the kernel and bridge/iproute2 recognize the "Isolated"
parameter, systemd-networkd did not have a way to set it.
