Hi
On 11/04/2014 02:49 AM, St챕phane Desneux wrote:
Hi Boram,
Could you, please, elaborate a little bit on the problem you're facing.
During developing our project, we(samsung) faced many issues which were
difficult to be analyzed in application side. So to analyze them in
xserver side powerfully and conveniently, we have developed
xf86-module-xdbg. xf86-module-xdbg consists of two parts. One is the
module(libxdbg.so) which is loaded during xserver is launching, and혻
another is a executable command(xdbg) which communicates with the
module(libxdbg.so) by using DBUS system bus. By using xdbg with root
right, we can trace x request, event, reply and error between xserver
and xclients.
However, when I tried to launch another second xserver, xdbg module got
failure when calling dbus_bus_get because xdbg uses one request
name(connection name?), previous xserver use .
To solve this issue, looks like xdbg needs to use different request
names for each xserver.
- name like xxxx.xdbg-{display number}
But if request name isn't fixed, I can't use bus configuration file in
/etc/dbus-1/system.d/. (I'm not expert. If wrong, correct me. :) )
So I was thinking about session bus.
Technically, as long as Xorg is launched inside a user session it will
have the DBUS_SESSION_BUS_ADDRESS set by systemd, as explained Maciej
previously.
NB: for weston, if weston-launch is used, it's not true as weston-launch
clears the environment before forking weston and thus doesn't propagate
the DBUS_SESSION_BUS_ADDRESS. My patch would also handle this corner
case; but it wasn't its main goal...
Well, this leaves me with 2 questions, regarding a multiuser system:
* why would we want to start xorg in a user session ? There's often only
one GPU and the users must be able to share it :)
As my understanding, we can launch xserver more than one ideally. One of
the ways launching Xorg is that user can call xorg-launch-helper in user
session. And xorg-launch-helper starts Xorg with root right. So above
issue can be potential problem.
* if it was started as a system component, why does Xorg would need to
know the DBUS session address (of a particular user) ? 'app' is dead, so
which user are we talking about ? I hope it's not 'guest' :)
For these reason, I was trying to use session bus in xserver side.
If you look at Tizen:Common/wayland images, you'll see that weston is
started as a system daemon and by no way it's aware of DBUS session
address(es). If we must make it aware of the user sessions, it could be
interfaced with logind (or tlm, or whatever handles the user sessions)...
I'll trying to other way not using session bus and your recommend also.
Thanks
Best regards,
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