Bug#855874: xserver-xorg-core: bug script runs dmesg, which does not work

[Sven Joachim <svenjoac@gmx.de>]

On 2017-02-27 11:09 +0100, Julien Cristau wrote:

> On 02/22/2017 07:49 PM, Sven Joachim wrote:
>> Package: xserver-xorg-core
>> Version: 2:1.19.1-4
>> Severity: normal
>> 
>> With the stock Debian kernel (as of version 4.8.4-1~exp1), normal users
>> can no longer run dmesg:
>> 
>> ,----
>> | $ LANG=C dmesg
>> | dmesg: read kernel buffer failed: Operation not permitted
>> `----
>> 
>> This means that the bug script does not collect drm information from
>> dmesg, as can be seen below. :-(
>> 
>> 
> Is there anything we can realistically do about this?

It would be possible to try and get the information from the journal,
like this:

--8<---------------cut here---------------start------------->8---
diff --git a/debian/xserver-xorg-core.bug.script b/debian/xserver-xorg-core.bug.script
index 47ee7b70f..91e9a0652 100644
--- a/debian/xserver-xorg-core.bug.script
+++ b/debian/xserver-xorg-core.bug.script
@@ -137,9 +137,16 @@ if [ -x /bin/udevadm ]; then
     echo
 fi
 
-if [ -x /bin/dmesg ]; then
+unset DMESG
+if [ -d /run/systemd/system ] && journalctl -n1 >/dev/null 2>&1; then
+    DMESG=journalctl
+elif dmesg >/dev/null 2>&1; then
+    DMESG=dmesg
+fi
+
+if [ -n "$DMESG" ]; then
     pecho "DRM Information from dmesg:"
-    dmesg | egrep -i 'drm|agp'
+    $DMESG -k | egrep -i 'drm|agp'
     echo
 fi
 
--8<---------------cut here---------------end--------------->8---

Of course there's no guarantee that it succeeds, but it at least has a
chance if the user is in the right groups.

The linux-image bug script asks the user to obtain the dmesg information
via sudo (if installed), not sure how you would like that.

Cheers,
       Sven