[OE-core] [PATCH] [RFC] udev-extraconf: update mount.sh to use /run/media instead of /media

[Denys Dmytriyenko]

On Sat, Mar 29, 2014 at 12:17:23PM -0300, Otavio Salvador wrote:
> Hello Denys,
> 
> On Fri, Mar 28, 2014 at 6:29 PM, Denys Dmytriyenko <denis at denix.org> wrote:
> > From: Denys Dmytriyenko <denys at ti.com>
> >
> > This is done to work around the issue of auto-mounting block devices
> > (i.e. SD cards) when root filesystem is still in read-only mode and
> > creating /media/<device> mount-points by udev is not possible. That
> > is due to udev (/etc/rcS.d/S03udev) getting started earlier than
> > checkroot (/etc/rcS.d/S10checkroot.sh) gets a chance to re-mount the
> > rootfs as read-write.
> >
> > Although, canonical FHS specifies /media/<device> as a mount point
> > for removable media devices, the latest 2.3 version was released in
> > 2004 and since then FreeDesktop/udisks and other tools adopted the
> > new /run/media/<user>/<device> location. That was done to overcome
> > read-only rootfs limitation, since /run is usually a tmpfs mounted
> > partition, plus avoid name-clash between users.
> 
> Agreed.
> 
> > For our embedded systems environment we assume single-user operation
> > and hence simplify mount point to just /run/media/<device>.
> 
> Please don't. I have customers using multiple users in an embedded
> device and so I think it is better to adopt udisks standard here
> instead of diverging from it without a reasoning.

I guess I should have phrased it a bit better...

This part is a system-wide automount. It gets to run even when no user is 
logged in. In order to do per-user mounting, some sort of session management 
is required. For example, udisks, we both mentioned, starts along with the 
session, when a user logs in, hence allowing per-user mounts.

Since this approach uses udev and gets triggered on addition or removal of 
block devices, described in the corresponding rules, it happens on system 
level and is not dependant on a session or logged in user. When a session 
based approach is used with udisks, these rules should be disabled though.

The two approaches are rather mutually exclusive, but both are valid. There 
are cases when this system-level automount is desired (e.g. in industrial use 
cases) since there are no users are ever expected to log in or interact with 
the system.

So, this is not meant to replace or provide session-based mounting...


> ...
> > diff --git a/meta/recipes-core/udev/udev-extraconf/mount.sh b/meta/recipes-core/udev/udev-extraconf/mount.sh
> > index cb57e47..3e4f21f 100644
> > --- a/meta/recipes-core/udev/udev-extraconf/mount.sh
> > +++ b/meta/recipes-core/udev/udev-extraconf/mount.sh
> > @@ -20,7 +20,7 @@ done
> >  automount() {
> >         name="`basename "$DEVNAME"`"
> >
> > -       ! test -d "/media/$name" && mkdir -p "/media/$name"
> > +       ! test -d "/run/media/$name" && mkdir -p "/run/media/$name"
> 
> Please see above...
> 
> ...
> 
> > --- a/meta/recipes-core/udev/udev-extraconf_1.0.bb
> > +++ b/meta/recipes-core/udev/udev-extraconf_1.0.bb
> > @@ -4,7 +4,7 @@ LICENSE = "MIT"
> >  LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=4d92cd373abda3937c2bc47fbc49d690 \
> >                      file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
> >
> > -PR = "r16"
> > +PR = "r17"
> 
> Don't change PR; in fact with this change I'd say to move it to 1.1 and drop PR.

I thought about it - either PV or PR needs to change. But I wasn't sure about 
bumping PV...

-- 
Denys