Re: [systemd-devel] Something wrong with sd_journal_add_match
On Wednesday 22 June 2016 12:10:14 Dennis Semakin wrote:
> The task is to obtain messages _only_ with specified fields (e.g.
> MESSAGE_ID=bla-bla-bla).
> And problem is that I can see incoming messages even when sending tool is
> not running (no execution). Looks like I got all messages from journal
> (kernel, other services, etc.).
> for (;;) {
>
> const void *data;
> size_t length;
>
> ret = sd_journal_next(sdj);
> if (ret == 0) {
> ret = sd_journal_wait(sdj, (uint64_t) -1);
> printf("wait ret = %d \n", ret);
> }
>
> sd_journal_get_data(sdj, "MESSAGE", , );
> printf(">%.*s<\n", (int) length, data);
I think I've seen something similar, so I'll note it here even if I'm not sure
if my understanding is correct:
sd_journal_wait() will trigger on *any* events, while sd_journal_get_data()
will apply the filter and find no matching entries.
I'm not sure why you see a consistent printing behavior, though. Can you check
the return value of sd_journal_get_data() in that case?
NB: I'm not much familiar with that codebase and haven't digged into the
source enough to confirm my speculation, so take it cum grano salis.
Cheers, Luca
--
«Доверяй, но проверяй»
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Re: [systemd-devel] Luks + lvm in initrd, tracking the issue
I've tracked down the issue a little. sysroot.mount requires/after dev-vg-lv.device. System start, dev-vg-lv is inactive. vgchange -a y - dev-vg-lv active. vgchange -a n - dev-vg-lv inactive. At this point, unit-job of dev-vg-lv is NULL (sometimes also happens when I don't run vgchange, but I still haven't been able to reproduce it). When sysroot.mount is started, job_is_runnable[1] checks for AFTER dependencies that have a non-NULL -job currently running. But dev-vg-lv is inactive, thus sysroot.mount fails to start. That also means the REQUIRES dependency of sysroot.mount to dev-vg-lv did not trigger the start the dev-vg-lv.device. Resuming: dev-vg-lv.device is inactive and has no job running, it's required/after yet it's not started when sysroot.mount is started. I have no deep knowledge of systemd internals to propose anything so I'd appreciate some feedback :) Best regards, [1] http://lxr.devzen.net/source/xref/systemd/src/core/job.c#429 ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Luks + lvm in initrd, complete scenario
Sorry for the spam. Further tracking down the issue. I think I've come to a conclusion of the scenario: S1.service requires/after D.device and S2.service S1 is activating, thus starts D and S2 S2 starts, which activates D and deactivates D A can now start because D has no job running [1], but D is not there anymore. Will try to create a couple of services to reproduce the problem. Best regards, [1] http://lxr.devzen.net/source/xref/systemd/src/core/job.c#429 ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] Luks + lvm in initrd
Hi, I'm going on with my work to have systemd in initrd on NixOS (using dracut is a little complicated at the moment). Everything works fine, I've ported luks and lvm and both work separately. However I'm hitting a problem when using luks and lvm on top of luks. SETUP Software: systemd 212, lvm 2.02.111, cryptsetup 1.6.3, kernel 3.14.22 The test is done with kvm. I have a device /dev/vda formatted with luks which gets opened in /dev/mapper/luksroot. Then lvm with a vg named vg and an lv named lv so that it gets named /dev/mapper/vg-lv. I have a sysroot.mount What=/dev/mapper/vg-lv and requires/after the cryptsetup service. The cryptsetup service runs systemd-cryptsetup attach luksroot /dev/vda. All fine, the luks gets opened correctly etc. PROBLEM Note I don't do any vgchange -a y, in any service, in any script. The /dev/vda appears, and then cryptsetup service runs. Luks is unlocked, /dev/mapper/luksroot and systemd tries to mount sysroot.mount. This is the problem, systemd does not wait for /dev/mapper/vg-lv to appear before mounting sysroot. In fact, it does not exist at all. It's like luksOpen + some udev rule tell udev/systemd that the device is there, but it's not. Note: if I disable the cryptsetup service, sysroot.mount correctly waits for /dev/mapper/vg-lv to appear. So the setup is pretty simple, I've read the udev rules however they're a little complex for my poor knowledge. The udev rules installed are all of lvm, dm. From systemd/udev it's: 60-cdrom_id.rules 60-persistent-storage.rules 80-drivers.rules 99-systemd.rules Any hints on where the culprit can be? Same happens with lvmetad. Best regards, ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] About systemd in initrd support
Thank you all for the replies. After the first answers I've ported the initrd to systemd (only the basic stuff, no luks, lvm, etc.) and works very fine. Except one thing, that I hoped to find in dracut but does not seem to do anything special about it. It just goes through switch-root it seems. As I understood it, systemctl switch-root will either run the specified init, or exec to the systemd in the new root. Looking a little through the code, it seems to do some kind of state-passing that I still have to study (--switched-root --deserialize etc.). Problem: in NixOS we need to run a further stage in the new root, before starting systemd. For example /etc is a symlink to a configuration tree which gets created at boot (we call it activation), and so on. Our init script activates the NixOS system and ultimately exec to systemd. initrd init - setup some env vars and mount points - systemd/initrd - switch-root - system activation script - systemd. Questions: 1) What are the advantages to let switch-root exec to systemd directly? Does executing it from our init is the same thing? 2) In case it's not the same thing, where is the best place to run that script? As a service in the new-root systemd? Thanks. Best regards, ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] About systemd in initrd support
As you already mentioned, you'd have to make sure you manage to pass through the state correctly. Thanks. Is there any docs I can read about this or just read the code? It appears that systemd dumps the state into a file, and afterwards it's passed to the new systemd instance. ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] About systemd in initrd support
I'm going to do an experiment with NixOS: replace the whole current initrd process made of scripts and hooks with systemd. Before doing any work however I'd like to hear whether systemd in initrd is still wanted in the future, or there's any possible idea about dropping this support. Also, apart arch linux, is there any other OS that you know using systemd for the whole initrd process? Thanks for you work. Best regards, -- www.debian.org - The Universal Operating System ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
