How to recover from a display driver problem

[Jim]

On 04/09/2016 06:53 PM, Karl Auer wrote:
> On Sat, 2016-04-09 at 16:47 -0500, Jim wrote:
>> when nothing else worked I decided to try  a different driver.
>> [...]
>> Anyone have any ideas of how to correct this without a complete
>> reinstall?
>
> Important note: I have never done this, this is a GUESS, and if it
> breaks, you own all the pieces.
>
> I believe that installing a new driver is nothing more complicated
> under the hood than a common "apt-get install ...". Recovering should
> be as easy as:
>
>    a) identify what packages you had before
>    b) re-install them.
>
> To do any of this however, you need a usable system you can execute
> commands on.
>
> If you can get out of your broken X to a text console (Alt-Ctl-F1), do
> so. If you can't get to a text console the easy way, you will need to
> go to single-user mode thusly:
>
> Boot into recovery mode and exit to a root shell. That will avoid
> starting X and will leave you in a text console as root. However, your
> filesystem will be read-only. Remount it writable like this:
>
>     mount rw -o remount,rw /dev/sda1
>
> Obviously adjust that for your particular drives and partitions.
>
> Now to locate the old package name.
>
> It may be possible to see what the old package was by doing "apt-get -s
> autoremove". If the old package is hanging around, it will be a
> candidate for autoremoval and will show up in the autoremove list. Havi
> ng thus identified it, you can just reinstall it.
>
> If the old package isn't in the autoremove list, you should be able to
> find it via the apt-get logs in /var/log/apts. The apt-get logs should
> go all the way back to your original install, though earlier ones may
> be gzipped.
>
> Look in the earliest logfile you have. I'm assuming it will have been
> archived, so you'll need to unzip it as below. If it isn't archived,
> substitute "cat" for "gunzip -c":
>
>     gunzip -c name_of_log_file.gz | less
>
> or this to pull out NVidia stuff:
>
>     gunzip -c history.log.2.gz | \
>          tr "," "\n"| \
>          grep -i nvidia | \
>          tr -d "(" \
>          cut -d\, -f2
>
> When I do this for Radeon (I have Radeon graphics hardware) I find:
>
>     libdrm-radeon1:amd64 2.4.64-1
>     xserver-xorg-video-radeon:amd64 7.5.0+git20150819-0ubuntu1
>
> The first part on each line is the package; the second part is the
> specific version of that package.
>
> Then install the old one(s) again using "apt-get install". You can
> leave the architecture marker (":amd64") out - apt-get should choose
> the right architecture automatically.
>
> If the new and old versions have the same package name, you will need
> to use the specific package version number when installing. Using my
> packages as examples:
>
>     apt-get install libdrm-radeon1:amd64=2.4.64-1
>     apt-get install
> xserver-xorg-video-radeon:amd64=7.5.0+git20150819-0ubuntu1
>
> ...note the equals sign.

I am at root. Pinging security.ubuntu.com says unknown host. I can ping 
127.0.0.1. Googling I found: ip route 8.8.8.8 |awk '{print $NF; exit}' 
and get: RTNETLINK answers: Network is unreachable.

So at root I can't seem to go out and get what I need to install and fix 
my problem.

Regards, Jim



>
> Reboot to check that X works again.
>
> Once you have it working, do "apt-get autoremove" to wipe unneeded
> packages, and "apt-get upgrade" to get the driver up to date.
>
> Regards, K.
>
> PS: Just to repeat: I have not done this myself, it is a GUESS as to
> how you might proceed. If anyone with actual experience pops up, listen
> to them, not me.
>