On 11/8/18 7:45 AM, unman wrote:
On Wed, Nov 07, 2018 at 08:14:23PM -0800, Ryan Tate wrote:
The latest is everything above and below the VMs is gone from the Qubes menu. The bottom
of the menu where I'd go to shut down just says "No applications found." The
top where I would go to find settings, Qubes Manager, even the dom0 Terminal is just
gone. So I don't even know how to debug. I've rebooting several times, it keeps happening.
Had you made any changes to the menu system?
Can you check the contents of /etc/xdg/menus/xfce-applications.menu to
make sure you still have a Menu item for System Tools. If you're not
sure just post the contents here.
There was a problem in the past with .desktop files disappearing.
can you make sure that you have .desktop files in
/usr/share/applications ?
unman
There is one consistently reproducible way to destroy the Qubes menu, by
simply using the built in xfce/other menu editor to reorganize your menu
entries, if you happen to be the impatient type in trying to get it
done. I have tried every menu editor I could find, and they all seem to
do pretty much the same damage.
Example:
1) Right click on the xfce/Qubes menu button.
2) Select properties from the popup menu
3) Select the edit menu button.
4) Select a sub-menu for any VM to edit
5) Select an entry on the right to move an application up/down in the list
6) Press the up or down button quickly in succession, say to move an
entry from the bottom of the list, up to the top of the list.
7) Save the menu.
Congratulations, you now have no Qubes menu at all, so lets hope you
still have a dom0 command window open.
To recover the menu, start a template vm via qvm-run, and run dnf to
update or make any change that in turn forces a dom0 resync of the Qubes
menu items. Or perhaps you can just force a resync from the dom0 command
line (qvm-sync-appmenus), but I have not tested that.
I believe (a wild *** guess, base on only visual clues and behavioral
evidence) the problem is that the editor rewrites a file upon each
'move' button click, and if you do it too quickly there is a concurrency
problem with re-opening the menu files that have not yet been
closed/flushed to disk. They may be reading and updating a partially
written menu file.
Do the same thing slowly and count-to-3 between mouse clicks, and there
is no problem. If you can hear your disk drive churning when clicking
the up/down button, when its quiet again, then it is ok to push the
button again.
I'm guessing this is an upstream xfce read/write/thread locking problem,
but the added complexity of the Qubes menu might be the reason for the
concurrency/timing issue due to more complexity overhead and Xen CPU
latencies. I'm guessing if you had a very simple xfce menu (e.g. the
default/simple xfce OS installation), and without Xen overhead, this
would likely not happen, thus the proper locking had never been
implemented. I have not yet had the luxury of the time to chase this
thread, to actually confirm my suspicion, so your mileage may vary. On
my system this is 100% reproducible.
Bottom line, don't be too quick with changes to the menu, or you will be
spending even more time repairing your system. The first time this
happened I had no clue how to recover.
Steve
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