[Sugar-devel] Wanting to know a bit of (NetworkManager) workflow upon resume-from-suspend

[Paul Fox]

martin wrote:
 > On Wed, May 2, 2012 at 3:22 AM, Ajay Garg <ajaygargnsit at gmail.com> wrote:
 > > The /etc/powerd/postresume.d/disable_mesh.sh  doesn't work.
 > 
 > So we need to understand why it does not work. Is it a race condition?
 > Perhaps it is better fixed as a udev script -- triggering when the
 > device appears.

i think it's almost a guaranteed race.  that script essentially 
does this:

    while [ ! -f /sys/class/net/eth0/lbs_mesh ]
    do
	sleep 0.5
    done
    echo 0 > /sys/class/net/eth0/lbs_mesh 

in other words -- the disable_mesh script will discover the disable
node at just about exactly the time that NM discovers the interface.

there's also the "lbs_disablemesh" module parameter, which could be
supplied at initial module load.  does that not work, for some reason?
(i seem to recall there may be a problem with it.)

paul

 > 
 > The step that disable_mesh performs is very important. If you don't
 > disable it at that level, you haven't disabled mesh at all and all the
 > problems persist.
 > 
 > >>  - disable mesh on boot
 > > Done. Added the 'echo 0' script in 'start()' method of NetworkManager, so
 > > that the effect takes place before NetworkManager starts up. Works like a
 > > charm.
 > 
 > Ok. Maybe a udev script is a better place.
 > 
 > >>  - disable mesh on resume, from a powerd-triggered script
 > > Does not work, as explained above.
 > 
 > Right but you MUST find a way to make it work.
 > 
 > >>  - blacklist the MAC address so NM ignores it
 > >>
 > >> you win. Yes, every XO has a different MAC address, but you can read
 > >> that on first boot of the OS, and write the NM configuration. See the
 > >> olpc-configure script for examples.
 > >
 > >
 > > Would be awesome. I believe this is the one and only complete solution
 > > possible :)
 > 
 > Careful here! This only hides the device from NM so you don't race with NM.
 > 
 > > Could you point me to the suitable (examples) link? I will be heartfully
 > > grateful.
 > 
 > look at the latest olpc-configure in git://dev.laptop.org/projects/olpc-utils
 > 
 > 
 > 
 > m
 > -- 
 >  martin.langhoff at gmail.com
 >  martin at laptop.org -- Software Architect - OLPC
 >  - ask interesting questions
 >  - don't get distracted with shiny stuff  - working code first
 >  - http://wiki.laptop.org/go/User:Martinlanghoff
 > _______________________________________________
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=---------------------
 paul fox, pgf at laptop.org