Re: [Xen-users] Apply changes after editing Xen files ?

[Stratos Skleparis <stratos.911@xxxxxxxxx>]

Dear George,

Thank you so much for the helpful tips / information, I checked the log but I am new into this and didn't get much out of it ! The reason I am modifying an older version of Xen hypervisor files and xend service is for educational purposes [university - life ]! When I am done with this version I will 100% try to modify a newer one :-)Â

Thanks again for your time,

-Stratos

On Mon, Dec 7, 2015 at 1:21 PM, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:

On Mon, Dec 7, 2015 at 8:48 AM, Stratos Skleparis <stratos.911@xxxxxxxxx> wrote:
> Dear all,
>
>Â I am experimenting on some Xen 4.1.2 version [running Ubuntu server
> 12.04] python files [ migrate.py , XendCheckpoint.py and XendDomain.py ]
> and making some changes on them . Thing is yesterday thought the changes
> were applied on the python files after just restarting xend service
> [sudo /etc/init.d/xend restart]

Out of curiosity, is there a reason you're using xend, rather than
modifying xl on a more recent system?

xend has been deprecated since 4.2, and was removed from tree just
after the 4.4 release. So most of my answers will be from memory, and
I don't have a lot of motivation to go back and install a xend system
to give you more accurate answers.

>Â After I restarted the system I couldn't get xend service to start..
>
> * Starting Xen daemons [OK]
>
>Â But whenever I typed sudo xm list I got this :
>
> Error: Unable to connect to xend: No such file or directory. Is xend
> running?

Did you check to see if xend was in fact running (by running "ps ax |
grep xend")?

Did you check to see if there were any error messages in
/var/log/xen/xend.log? *

* Not sure that's the exact name -- see above re xend being deprecated

>Â So I am thinking of formating my setup and starting all over again
> because I don't understand what's going on.. :/ [I can provide you the
> logs if possible]

Simply removing the ubuntu package (apt-get remove $package) and
re-installing it should be enough to restore the original files, I
would think.

> In case this doesn't happen again how can I check-debug the changes I
> have made on Xen before restarting the system [why couldn't i get the
> error on the first place]??
>
>Â Since this is a lengthy procedure simply restarting Xend service is
> enough to apply changes on python files or am I missing something else
> that crashed my system and I couldn't see it in the first place ?

Restarting xend should be enough to get your changes. From what you
describe, it's likely that xend *did* get your changes, but that you
made a mistake which caused it to crash. The reason for the crash is
likely in the xend log (in /var/log/xen/$something).

FWIW what most developers do is check out the source tree in git, and
run a command "make debball", which will give you a really basic
debian package you can install. git is designed for exactly the
scenario you describe -- "how do I get back to a previous version of
the files". Not sure when the "make debball" feature was introduced
-- I'm pretty sure it was there by 4.2. If you're re-building your
own, and you *really* want xend, your best bet is probably to go to
4.4 (the last release with xend in it).

Â-George

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