78 mount points on armhf image

[Dustin Kirkland]

On Wed, Mar 9, 2016 at 11:44 AM, Oliver Grawert <ogra at ubuntu.com> wrote:
> hi,
> Am Mittwoch, den 09.03.2016, 11:30 -0500 schrieb Mike Carifio:
>> I might be sending this email to wrong list. Won't be the first time.
>> Sorry if so.
>>
>> Using these ubuntu section of these directions
>> https://developer.ubuntu.com/en/snappy/start/raspberry-pi-2/ and this
>> image
>> https://people.canonical.com/~mvo/all-snaps/rpi2-all-snap.img.xz,
>> I was able to install snappy on an rpi 2 model b. Other than some
>> fumbling around with sdcards, getting the display to show hdmi, etc,
>> this was easy enough for even me. Thank you.
>>
>> Some follow on questions:
>>
>> * mount | wc -l shows 78 (!) mount points. Yikes. Why? Guess I'll
>> need
>> to brush up on partition mounting.
> snappy uses a readonly image ... to have some files and dirs writable
> we ue a "bind mount farm" (the alternative would be some kind of
> overlayfs but this would enforce support for the chosen fs type in teh
> kernel which we want to avoid) to actually mount these files into the
> writable file space. while this is a bit ugly in the mount output, it
> is very fine grained (so very secure) and also avoids extra filesystem
> layers that potentially could affect performance.

Along these lines, the output of the "mount" command, while machine
readable, is not columnized, and is not very human readable.

Contrast the output of "mount" and "ps -ef".  Both return many lines
of output, but the ps output is so much more readable.

Consider instead piping the output of mount through column -t.  "mount
| column -t".  Much more readable.  There are a couple of useless
columns (on, type), but I find this much more human readable.  It
makes me think there should be a pretty print option to mount, perhaps
"-H' for "human readable", tabular output.

Dustin

>>
>> * Unless I'm confused, it looks like /dev/mmcblk0p2 is mounted
>> multiple
>> times.
>>
> yes, this is how bind mounts are represented in the mount output.
>
>> * Is there a rpi 3 model b image? As I understand it, 3 is armhf but
>> 64
>> bits, so rpi2-all-snap won't work (although I did try).
> the rpi3 while being a 64bit arch does not support 64bit at all yet,
> you need to run 32bit userspace on it until the binary bootloader can
> actually initialize the hardware in a 64bit mode, i assume broadcom
> will soon provide the binary blobs for this.
>
> as the person currently caring for the rpi images i took a brief look
> last weekend.
>
> snappy makes heavy use of u-boot features, the port of u-boot to the
> rpi3 is still in very early stages (i assume it is only a matter of
> weeks though). we also use a "close to mainline" kernel in snappy that
> is currently missing some patches for the rpi3 i think. once these bits
> are available i will try to make an rpi3 image (or even try to get the
> current 32bit image to work on both devices).
>
> ciao
>         oli
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