[OE-core] [PATCH 1/2] busybox-mdev: Support automatic mounting of block devices

[Mike Looijmans]

On 12/18/2014 01:55 PM, Otavio Salvador wrote:
> Hello Mike,
>
> On Thu, Dec 18, 2014 at 4:31 AM, Mike Looijmans <mike.looijmans at topic.nl> wrote:
>> On 12/17/2014 11:08 PM, Gary Thomas wrote:
>>>
>>> On 2014-12-17 15:03, Burton, Ross wrote:
>>>>
>>>> Hi Mike,
>>>>
>>>> On 5 December 2014 at 09:58, Mike Looijmans <mike.looijmans at topic.nl
>>>> <mailto:mike.looijmans at topic.nl>> wrote:
>>>>
>>>>      Upon inserting a USB stick or similar device, mdev will run
>>>>      an automounter script that mounts valid partitions on
>>>>      /media/<device>. The script first checks /etc/fstab entries
>>>>      so that mounting on UUID or LABEL or using custom mount options
>>>>      is still possible. If /etc/fstab does not contain particular
>>>>      mount options, the script will create (and remove) the mountpoint
>>>>      automatically.
>>>>      The script also supports full disk partitions (devices without
>>>>      partition table).
>>>>
>>>>
>>>> Thanks for this, but can this script be put into a separate recipe to
>>>> make
>>>> it even easier for people who don't want it, or want their own version?
>>>> The
>>>> prior art here is the udev
>>>> automounting script which is in udev-extraconf.
> ...
>
> I didn't try but what happens in mdev if the script does not exists? I
> mean keep mdev.conf as is (ready for use) and move the script to
> another package which can be installed or not.

I just tried, removed the script and inserted a stick. It still created 
/dev/sda and /dev/sda1 so it seems nothing really bad will happen then.

>> On the satellite settop boxes, /media is a 64k tmpfs mount. This is because
>> when a mount fails, the box may end up writing a TV recording to wherever
>> /media happens to be. It that's flash or a big tmpfs, the box will commit
>> suicide in mere seconds by either filling the flash or eating up the
>> precious RAM. And for some things, the box really needs a big tmpfs, so just
>> reducing the volatiles' sizes wasn't an option.
>
> Nice 'solution' to avoid a more serious problem :-D

Well, it got rid of tons of "check if this and that" code in the recorder code 
which occasionally would still be fooled into recording onto flash or RAM.

>> Having said that, if this is blocking, I'll do a s./media./run/media.g on
>> the file, getting this mainlined has higher priority.
>
> I prefer to have it behaving as udev as much as possible, by default.
> However, the script could source a defaults file (if it exists) to
> change the mounting point for example and allow for those special
> systems to be handle without forking.

Yeah, something like "MDEV_AUTOMOUNT_ROOT=/media" in /etc/default/mdev should 
do the trick.



Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


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