Re: [systemd-devel] Generic unit file to run command on shutdown impossible?
On Sat, 10.08.13 15:59, David Mazieres expires 2013-11-08 PST (mazieres-rq54ugpgb894kkmq2swhjjb...@temporary-address.scs.stanford.edu) wrote: > I'm trying to do something that I hope is relatively simple, namely to > run a simple kexec -l ... command on system shutdown before the /boot > file system is unmounted. I'm trying this on two different machines, > both of which are running current versions of arch linux with systemd > 204. The machines are configured very similarly, except that one has > a serial console and some NFS mounts, while the other does not. > Unfortunately, I cannot find a single script that works on both > machines. > > On the machine with a serial console, the following unit file seems to > work (in /etc/systemd/system/kexec-load@.service, enabled with > systemctl enable kexec-load@linux). This is a slightly modified > version of a suggestion on the arch linux wiki: It's usually a better idea to have this as unit that starts at bootup, and stops at shutdown, rather than one that starts at shutdown. This is because of the orderign semantics of start and stop jobs. The general rule here is that if one job is started and one is stopped and there is either After= or Before= defined between their two units, then the Stop= is always run first, and the start second, regardless whether After or Before was used. After/Before= hence only declare the ordering between two start jobs, and the ordering between two stop jobs (where the rule is that it is the inverse of the start order), but not between a start and a stop job. This might be confusing, but not too difficult to grok I guess.. Effectively this means that you should define a RemainAfterExit=yes service with ExecStart=/bin/true and ExecStop= set to what you want to run at shutdown. The requirement to set an ExecStart= is something we will lift soon, but for now it is required. I hope this makes some sense? Lennart -- Lennart Poettering - Red Hat, Inc. ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] Generic unit file to run command on shutdown impossible?
I'm trying to do something that I hope is relatively simple, namely to run a simple kexec -l ... command on system shutdown before the /boot file system is unmounted. I'm trying this on two different machines, both of which are running current versions of arch linux with systemd 204. The machines are configured very similarly, except that one has a serial console and some NFS mounts, while the other does not. Unfortunately, I cannot find a single script that works on both machines. On the machine with a serial console, the following unit file seems to work (in /etc/systemd/system/kexec-load@.service, enabled with systemctl enable kexec-load@linux). This is a slightly modified version of a suggestion on the arch linux wiki: [Unit] Description=load %i kernel into the current kernel Documentation=man:kexec(8) DefaultDependencies=no Before=shutdown.target umount.target final.target After=sysinit.target [Service] Type=oneshot ExecStart=/usr/bin/kexec -l /boot/vmlinuz-%i --initrd=/boot/initramfs-%i.img --reuse-cmdline [Install] WantedBy=kexec.target However, when I try this script on the machine without a serial console, the script gets run at the very end of the shutdown process, after all the file systems are unmounted (and hence at a point where the new kernel image is unavailable). I can boot with systemd.log_level=debug, but since there's no serial console and I can't get my job to fire before the journal system is shutdown, it's hard for me to capture all the output on shutdown. Conversely, I devised a kind of hacky way to make it work on the non-serial-console machine what doesn't work on the serial console one. Here my idea is to have a job whose ExecStop loads the new kernel. I'm not sure why that job fires only on startup and not shutdown of the serial console machine, but if I solve one of these problems, I'd rather get the WantedBy=kexec.target approach working, if that's possible, so I'll omit the details for now. For what it's worth, here's a relevant subset of the output of the systemd --test command on the machine that does not work (i.e., the non-serial console) with the above unit file: /usr/lib/systemd/systemd --system --test --unit=kexec.target -> By units: -> Unit shutdown.target: After: kexec-load@linux.service ReferencedBy: kexec-load@linux.service -> Unit systemd-journald.socket: Before: kexec-load@linux.service ReferencedBy: kexec-load@linux.service -> Unit sysinit.target: Before: kexec-load@linux.service ReferencedBy: kexec-load@linux.service -> Unit final.target: After: kexec-load@linux.service ReferencedBy: kexec-load@linux.service -> Unit umount.target: After: kexec-load@linux.service ReferencedBy: kexec-load@linux.service -> Unit kexec.target: Wants: kexec-load@linux.service References: kexec-load@linux.service -> Unit kexec-load@linux.service: Name: kexec-load@linux.service Fragment Path: /etc/systemd/system/kexec-load@.service -> ExecStart: Command Line: /usr/bin/kexec -l /boot/vmlinuz-%i --initrd=/boot/initramfs-%i.img --reuse-cmdline So here the dependencies seem fine. Yet when I look at the "by jobs" category: -> By jobs: -> Job 3: Action: kexec.target -> start State: waiting Forced: no Irreversible: no -> Job 4: Action: systemd-kexec.service -> start State: waiting Forced: no Irreversible: no -> Job 5: Action: shutdown.target -> start State: waiting Forced: no Irreversible: no -> Job 83: Action: umount.target -> start State: waiting Forced: no Irreversible: no -> Job 88: Action: boot.mount -> stop State: waiting Forced: no Irreversible: no -> Job 90: Action: final.target -> start State: waiting Forced: no Irreversible: no -> Job 91: Action: kexec-load@lin
