[systemd-devel] systemd.volatile=yes

Lennart Poettering lennart at poettering.net
Tue Sep 5 07:16:12 UTC 2017


On Mo, 04.09.17 13:48, Tobias Hunger (tobias.hunger at gmail.com) wrote:

> Hi Lennart,
> 
> On Mon, Sep 4, 2017 at 11:06 AM, Lennart Poettering
> <lennart at poettering.net> wrote:
> > Hmm, mount.usr= should continue to be supported. It's documented in
> > the systemd-fstab-generator man page however, not in the
> > kernel-command-line one. We should fix that however, can you file a
> > bug?
> 
> I'll file a merge request for that this week. I guess this is not that urgent;-)
> 
> >> The one pitfall I ran into is that I had to add a "usr" folder into
> >> the usr partition for systemd-volatile-root.service to work. The
> >> system boots well and seems to work nicely with this change.
> >
> > Uh, this shouldn't be necessary. Can you file a bug? I am really
> > surprised by this I must say... In my testing it didn't do that
> > either...
> 
> src/volatile-root/volatile-root.c line 53: return log_error_errno(r,
> "/usr not available in old root: %m");
> 
> Rereading the documentation on systemd.volatile, that is also pretty
> much exactly what it says there: "[...] only /usr is mounted from the
> file system configured as root device, in read-only mode.". My
> assumption was that I can take a usr-partition as is (the one I used
> to use with mount.usr*) is wrong, I need to move things down one
> level.

Oh right of course, we make this requirement so that you can take a
normal root fs, and boot it with systemd.volatile= sometimes but not
always, i.e. that you can choose on every boot whether you want to
boot in stateful or stateless mode. Or to say this differently: that a
root fs may contain /etc and /var and all that garbage, but if you
boot in volatile mode these are ignored, and only /usr is used.

Lennart

-- 
Lennart Poettering, Red Hat


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