CentOS virt - Nov 2015 - new install of Xen 4.6 hangs on Loading initial ramdisk

First post to this list.  I would appreciate some help on this issue.

As background, I installed CentOS 7 on a Dell server, and then ran the following
commands:

yum update
http://buildlogs.centos.org/centos/7/virt/x86_64/xen/centos-release-xen-7-11.el7.x86_64.rpm
yum --enablerepo=centos-virt-xen-testing update
yum --enablerepo=centos-virt-xen-testing install xen

Doing that, I was able to successfully install Xen, create a virtual machine
with its own HVM setup, logical volume, etc. and boot it just fine.

I then tried to do the same on an IBM x3550 server I?m trying to install with
CentOS 7.  The CentOS 7 install went just fine.  I can boot into the standard
kernel and have a working machine.  But after running the commands above to
install the Xen hypervisor, the machine hangs on boot for a few moments after
displaying the lines below and then reboots in a loop over and over and over:

Loading Xen 4.6.0-2.el7 ?
Loading Linux 3.18.21-16.el7.x86_64 ?
Loading initial ramdisk ?

It never gets beyond that.  If I choose the stock kernel (no Xen) from the Grub
menu, it will continue to boot into that just fine.

My grub.cfg file has these entries of note:

 multiboot	/xen-4.6.0-2.el7.gz placeholder  dom0_mem=1024M,max:1024M cpuinfo
com1=115200,8n1 console=com1,tty loglvl=all guest_loglvl=all ${xen_rm_opts}
        echo    'Loading Linux 3.18.21-16.el7.x86_64 ...'
        module  /vmlinuz-3.18.21-16.el7.x86_64 placeholder
root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde ro crashkernel=auto debug irqpoll
ipv6.disable=1 console=hvc0 earlyprintk=xen nomodeset
        echo    'Loading initial ramdisk ...'
        module  --nounzip   /initramfs-3.18.21-16.el7.x86_64.img


What I have tried:

1) adding debug into the vmlinuz line
2) disabling ipv6 in that line
3) adding root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde to the last line AFTER
/initramfs ?.

Nothing so far has made any difference.  Obviously the process works, as it
works for me just fine on the Dell server.

Underlying this machine is a SATA RAID 1 PCI card with two SSD drives attached
in a RAID 1 mirror.  Not that that should matter, but I?m including it for
reference. As noted previously, it boots into the stock kernel just fine.

Any help would be appreciated.

--
Craig Thompson, President
Caldwell Global Communications, Inc.
423-559-5465




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On Fri, Nov 27, 2015 at 06:18:05PM -0500, Craig Thompson
wrote:
>    First post to this list.  I would appreciate some help on this issue.
>    As background, I installed CentOS 7 on a Dell server, and then ran the
>    following commands:
>    yum update
>   
[1]http://buildlogs.centos.org/centos/7/virt/x86_64/xen/centos-release-xen-7-11.el7.x86_64.rpm
>    yum --enablerepo=centos-virt-xen-testing update
>    yum --enablerepo=centos-virt-xen-testing install xen
>    Doing that, I was able to successfully install Xen, create a virtual
>    machine with its own HVM setup, logical volume, etc. and boot it just
>    fine.
>    I then tried to do the same on an IBM x3550 server I*m trying to install
>    with CentOS 7.  The CentOS 7 install went just fine.  I can boot into
the
>    standard kernel and have a working machine.  But after running the
>    commands above to install the Xen hypervisor, the machine hangs on boot
>    for a few moments after displaying the lines below and then reboots in a
>    loop over and over and over:
>    Loading Xen 4.6.0-2.el7 *
>    Loading Linux 3.18.21-16.el7.x86_64 *
>    Loading initial ramdisk *
>    It never gets beyond that.  
>
Weird. So you don't see any output from Xen? 

I guess that means GRUB gets stuck somehow, and doesn't even get to actually
starting Xen..

> If I choose the stock kernel (no Xen) from the
>    Grub menu, it will continue to boot into that just fine.
>    My grub.cfg file has these entries of note:
>     multiboot         /xen-4.6.0-2.el7.gz placeholder
>    dom0_mem=1024M,max:1024M cpuinfo com1=115200,8n1 console=com1,tty
>    loglvl=all guest_loglvl=all ${xen_rm_opts}
>            echo    'Loading Linux 3.18.21-16.el7.x86_64 ...'
>            module  /vmlinuz-3.18.21-16.el7.x86_64 placeholder
>    root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde ro crashkernel=auto debug
>    irqpoll ipv6.disable=1 console=hvc0 earlyprintk=xen nomodeset
>            echo    'Loading initial ramdisk ...'
>            module  --nounzip   /initramfs-3.18.21-16.el7.x86_64.img
>    What I have tried:
>    1) adding debug into the vmlinuz line
>    2) disabling ipv6 in that line
>    3) adding root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde to the last
line
>    AFTER /initramfs *.
>    Nothing so far has made any difference.  Obviously the process works, as
>    it works for me just fine on the Dell server.
>    Underlying this machine is a SATA RAID 1 PCI card with two SSD drives
>    attached in a RAID 1 mirror.  Not that that should matter, but I*m
>    including it for reference. As noted previously, it boots into the stock
>    kernel just fine.
>    Any help would be appreciated.
>
Yeah it's not about options to Xen and/or Linux when GRUB fails to boot the
entry in the first place..

Is this UEFI setup? Or legacy-BIOS? Did you try playing with the BIOS options? 


-- Pasi
>    --
>    Craig Thompson, President
>    Caldwell Global Communications, Inc.
>    423-559-5465
>

On Fri, Nov 27, 2015 at 11:18 PM, Craig Thompson <
president at caldwellglobal.com> wrote:
> First post to this list.  I would appreciate some help on this issue.
>
> As background, I installed CentOS 7 on a Dell server, and then ran the
> following commands:
>
> yum update
>
http://buildlogs.centos.org/centos/7/virt/x86_64/xen/centos-release-xen-7-11.el7.x86_64.rpm
> yum --enablerepo=centos-virt-xen-testing update
> yum --enablerepo=centos-virt-xen-testing install xen
>
> Doing that, I was able to successfully install Xen, create a virtual
> machine with its own HVM setup, logical volume, etc. and boot it just fine.
>
> I then tried to do the same on an IBM x3550 server I?m trying to install
> with CentOS 7.  The CentOS 7 install went just fine.  I can boot into the
> standard kernel and have a working machine.  But after running the commands
> above to install the Xen hypervisor, the machine hangs on boot for a few
> moments after displaying the lines below and then reboots in a loop over
> and over and over:
>
> Loading Xen 4.6.0-2.el7 ?
> Loading Linux 3.18.21-16.el7.x86_64 ?
> Loading initial ramdisk ?
>
> It never gets beyond that.  If I choose the stock kernel (no Xen) from the
> Grub menu, it will continue to boot into that just fine.
>
> My grub.cfg file has these entries of note:
>
>  multiboot /xen-4.6.0-2.el7.gz placeholder  dom0_mem=1024M,max:1024M
> cpuinfo com1=115200,8n1 console=com1,tty loglvl=all guest_loglvl=all
> ${xen_rm_opts}
>         echo    'Loading Linux 3.18.21-16.el7.x86_64 ...'
>         module  /vmlinuz-3.18.21-16.el7.x86_64 placeholder
> root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde ro crashkernel=auto debug
> irqpoll ipv6.disable=1 console=hvc0 earlyprintk=xen nomodeset
>         echo    'Loading initial ramdisk ...'
>         module  --nounzip   /initramfs-3.18.21-16.el7.x86_64.img
>
>
> What I have tried:
>
> 1) adding debug into the vmlinuz line
> 2) disabling ipv6 in that line
> 3) adding root=UUID=9dc18146-f9b3-41cc-ba9c-7314689abcde to the last line
> AFTER /initramfs ?.
>
> Nothing so far has made any difference.  Obviously the process works, as
> it works for me just fine on the Dell server.
>
> Underlying this machine is a SATA RAID 1 PCI card with two SSD drives
> attached in a RAID 1 mirror.  Not that that should matter, but I?m
> including it for reference. As noted previously, it boots into the stock
> kernel just fine.
>
> Any help would be appreciated.
>
Thanks for the testing and the report.

Have you tried booting the Xen4CentOS kernel (Linux-3.18.21-16) by itself
(i.e., not under Xen)?

Also, is there any chance you could get the output of a serial console?
That's pretty critical for debugging this sort of thing.

 -George
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