Re: [PATCH 1/2] wic: When using --use-uuid make sure that we update the fstab with PARTUUID

[Ed Bartosh <ed.bartosh@linux.intel.com>]

On Mon, Nov 06, 2017 at 07:44:23AM -0500, Tom Rini wrote:
> On Mon, Nov 06, 2017 at 09:36:20AM -0200, Otavio Salvador wrote:
> > On Mon, Nov 6, 2017 at 8:08 AM, Ed Bartosh <ed.bartosh@linux.intel.com> wrote:
> > > On Fri, Nov 03, 2017 at 08:51:50AM -0400, Tom Rini wrote:
> > >> On Fri, Oct 20, 2017 at 09:15:05AM -0400, Tom Rini wrote:
> > >> > On Tue, Oct 10, 2017 at 05:01:49PM -0400, Tom Rini wrote:
> > >> > > On Thu, Sep 21, 2017 at 01:46:16PM -0400, Tom Rini wrote:
> > >> > > > When we have been told to use the UUID we should also update the fstab
> > >> > > > to make use of PARTUUID instead of hard-coding the device in question.
> > >> > > > This will make the resulting image much more portable.
> > >> > > >
> > >> > > > Signed-off-by: Tom Rini <trini@konsulko.com>
> > >> > > > ---
> > >> > > >  scripts/lib/wic/plugins/imager/direct.py | 9 ++++++---
> > >> > > >  1 file changed, 6 insertions(+), 3 deletions(-)
> > >> > >
> > >> > > Where we did we end up with this?  Ed pointed out that you can tell wic
> > >> > > to use a specific UUID, so reproducible images are not a problem.  And
> > >> > > making images that are readily portable is why other distros use
> > >> > > UUID/LABEL and not device names as much as possible.  I personally enjoy
> > >> > > being able to put an image on uSD for minnow and have it work :)
> > >> > > Thanks!
> > >> >
> > >> > ping?
> > >>
> > >> I was just reminded about the real problems this solves (swap isn't
> > >> /dev/sda3, boot is being excessively slow), so, ping?
> > >>
> > >
> > > I'm generally ok with the patchset. The only thing I'm thinking of is if busybox mount
> > > supports PARTUUID syntax in fstab. Can you check this, please?
> > 
> > It does.
> 
> It doesn't, you need util-linux for a mount that figures these out (or,
> it did when I wrote the patch set).

This practically means that this patch makes it impossible to use
--use-uuid for busybox-powered images. This is quite a big regression
from my point of view. We need to make this feature optional then.

>  That's why 2/2 only updates the
> systemd canned wks as that _will_ have full mount.  But please note that
> you can already make a wks file that doesn't work with busybox mount by
> using the --use-uuid flag for non-root partitions :)
>
What's the point of using --use-uuid for non-root partitions? I thought
it only makes sense for root as it triggers update of kernel command
line.


> > > I'd like to see Otavio's confirmation that --uuid option solves
> > > his reproducible builds concern.
> > 
> > I am not against it if the no-fstab-update consider this too. Using
> > uuid when making a fstab makes more sense but the possibility to not
> > touch the fstab must be kept.
> 
> Right.  I'm only updating the systemd wks file to use this.  Nothing
> forces this option to be globally used.

--
Regards,
Ed