Ubuntu 18.04 and SysRq magic


My system is now meant to dual boot between Mint 17.3 and Ubuntu 18.04.  However my Ubuntu install seems to stop during boot (it does however go in to recovery mode, including a GUI with few issues).  So it could be a driver issue, it was suggested on IRC it could be a graphics driver issue, so I asked why does the live CD work, response to that was ‘good point’

As I am able to use alt-SysRq RSEIUB to cleanly restart the system.  I am looking in to the SysRq functions to see if I can find anything that can help figure out what the problem may be.

A duckduckgo search first gave me a link to Enabling these functions.  This in turn lead me to more comprehensive documentation here.   Which provides a really good overview of the what you can do with SysRq

On Mint the

cat /proc/sys/kernel/sysrq

contains a value of 176,  which from the table can be calculated as follows

128+32+16 = 176

Which from the 2nd link I provided above will provide the following functions

128 =  0x80 - allow reboot/poweroff
32 =  0x20 - enable remount read-only
16 =  0x10 - enable sync command

Which is just a few of the available options, this is what is provided by default in Mint,  Reading further if I put the value of 1 in /proc/sys/kernel/sysrq I should be able to enable everything.

So back to my Ubuntu problem.  Booting stops at the following messages during boot (press esc to remove the splash-screen and view messages)

Started session c1 of user gdm (so related to the gnome display manager)

Started user manager for uid 120

After which,  the system boot process does not go any further.  It appears hung, but the Alt-SysRq functions work to reboot the system,  so it is now a case of trying to display some of the other messages and work out what the issue is.

Anyway, hopefully, after a bit of reading I can figure some more useful things out.,   The above kernel documentation prints nicely on a4, landscape on about 10 pages at font size 14.   if you print directly from the page the font size is tiny.   Copied in to Libreoffice, made the font a sensible size and printed out.

Another idea I had was to try installing on to a netbook and see if that has the same issue during boot,  I want to rule out a fault with the CD’s as they were created soon after the ISO release,  not that it should matter as I enabled updates during the install process.   Unless of course the updates are causing the issue. One step at a time.


If it helps some system info:-

CPU~Dual core Intel Core2 Duo E7500 (-MCP-) speed/max~2035/2926 MHz Kernel~4.13.0-39-generic x86_64 Up~2:19 Mem~1494.3/2971.8MB HDD~660.1GB(8.1% used) Procs~176 Client~Shell inxi~2.2.35

inxi -G
Graphics: Card: Intel 82Q35 Express Integrated Graphics Controller
Display Server: X.Org 1.18.4 drivers: intel (unloaded: fbdev,vesa)
Resolution: 1600×900@60.00hz
GLX Renderer: Mesa DRI Intel Q35 GLX Version: 1.4 Mesa 17.2.8