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Re: [Xen-users] Xen Continuously Reboots



>To: xen-users@xxxxxxxxxxxxx
>From: Daniel Widenfalk <Daniel@xxxxxxxxxxxx>
>Date: Wed, 8 Jun 2016 17:44:33 +0200
>Delivery-date: Wed, 08 Jun 2016 15:45:55 +0000
>List-id: Xen user discussion <xen-users.lists.xen.org>

>On 2016-06-08 14:48, Ray wrote:
>Date: Tue, 7 Jun 2016 13:48:12 -0700
>From: "russo@xxxxxxxxxxxxxxxxxxx" <russo@xxxxxxxxxxxxxxxxxxx>
>To: xen-users@xxxxxxxxxxxxx
>Subject: Re: [Xen-users] Xen Continuously Reboots
>Message-ID: <5757330C.4050501@xxxxxxxxxxxxxxxxxxx>
>Content-Type: text/plain; charset=utf-8; format=flowed
>You maybe allocating too much memory to your guests.
>Russo,
>Thank you.  I can really use the help as I have not been able to get a
>VM running yet.
>The machine has 16 GB of RAM.  I had included a line to limit the guest
>RAM to 2GB.  Xen would still not boot.  Then I removed the limits and
>still Xen would not boot.
>As far as I can tell you've yet to manage to boot your Dom0 so
>your guests have not yet started. You can also assign a hard locked
>amount of memory to your Dom0 and disable balooning (the process of
>dynamically adjusting the amount of memory that a guest have available).
 
I only have two choices in booting, one is Debian, the other is Xen.  I can boot to Debian (dom0), but not to Xen.

>Would a VM with a high RAM demand stop Xen from booting?  I thought a VM
>would not run until after Xen us up.  I could delete the VM
>configuration and try to boot to Xen, then there would be no VM demand
>on memory.
>I would suggest you disable (i.e. move the config files to a safe
>location) rather than deleting your domUs. First priority should be
>to get your dom0 booted and you logged in as root :)
I like the idea of disabling the VM by moving it.  I wonder what I am missing, Debian boots, isn't that my dom0.
 
>What xen options have you set up in /etc/default/grub? My
>GRUB_CMDLINE_XEN does not contain anything related to the vga
>console so that should not be an issue. (don't forget to run
>update-grub! I'm forgetting it about every other update...)

I have nothing in grub for Xen cmdline.  I do not have a desktop, I am running commend line only.  I am trying to keep the instance as minimal as possible.  I did have a vga statement for stretch so I removed that, updated grub and reboot.  The system still hangs.  So I removed the Linux cmdline for screen resolution - the display is a 4k and is difficult to read with the default resolution.  After update and reboot, the system still hangs. 
 
>When you do a bare metal boot of your linux, is your graphics
>driver being loaded as a module or are you using ye good old
>vga console?
 
I don't have anything in grub for vga.  I don't recall/know if ther was some  other way of modifying the display.  I have done something as Debian is readable so it is lower resolution than the default.
>Is your dom0 set up to use a desktop or are you booting a text-mode
>server only system? It might be worth disabling anything desktop:y
>until you've sorted the boot issues.
 
No desktop, text-mode only.
>I've swapped over my dom0 to use the sysv init system (I'm an old dog,
>don't want to learn to sit in a new fancy way) but remember that there
>was a significant delay from the first boot message until I got access
>to my console. How long have you waited? (I'm guessing 60+ seconds)
 
Stretch boots in nine seconds.  I have let Xen set for 5 mins to see if it will boot.  When the system hangs, I have not found a way to  break in.
 
Ray

>Regards

>/Daniel W

>Ray


>On 06/06/2016 12:49 AM, Daniel Widenfalk wrote:
>> On 2016-06-06 03:22, Ray wrote:
>>> 
>>> Re: [Xen-users] Xen Continuously Reboots
>>> 
>>> 
>> To: xen-users@xxxxxxxxxxxxx
>> From: Daniel Widenfalk <Daniel@xxxxxxxxxxxx>
>> Date: Sun, 5 Jun 2016 22:52:36 +0200
>> Delivery-date: Sun, 05 Jun 2016 20:53:33 +0000
>> List-id: Xen user discussion <xen-users.lists.xen.org>
>> 
>>>> On 2016-06-05 20:11, Ray wrote:
>> 
>>>> When I boot to Xen, the machine reboots over and over. This is a
>>>> laptop
>>>> with stretch and Xen.
>> 
>>>> <snipped>
>> 
>> 
>>>> Ray
>> 
>>> * Are you using EFI or legacy boot?
>>> * How far do you get? Do you get the quick "Loading XEN..." thing at
>>> the
>>> start? Do you start seeing the xen pre-boot phase?
>> 
>>> /Daniel W.
>> ______________________________
>> 
>> 
>> Daniel,
>> 
>> 
>> Thank you:
>> 
>> 
>> This is an EFI boot.
>> 
>> 
>> Once at the boot menu and the 5 seconds lapsed, the system went blank
>> and started booting.
>> 
>> Ray

> Hi,

> I've found that both Jessie and Stretch seem to have an error in their
> grub code for xen. The grub code does not recognize "efi" as a valid
> grub platform and therefore applies no-real-mode and eff=off to xen.
> "no-real-mode" means you will not get a VGA console and edd=off means
> xen will not fetch "Extended Disc Data" (whatever that means) from the
> bios.

> On my new system I had to edit /etc/grub/20_linux_xen (line 126) and
> add "efi" as a recognized boot platform:

> ---- Lines 125 - 30:
> echo '$(echo "$xmessage" | grub_quote)'
> if [ "\$grub_platform" = "pc" -o "\$grub_platform" = "efi" -o
> "\$grub_platform" = "" ]; then
> xen_rm_opts=
> else
> xen_rm_opts="no-real-mode edd=off"
> fi
> ----

> After making this change I got a working xen/linux vga console and could

> see what was going on. I hope this helps :)

> Best regards

> /Daniel Widenfalk

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