On 09/01/16 04:24, Pat Riehecky wrote:
> On 01/04/2016 05:13 PM, Steven Haigh wrote:
>> On 2016-01-05 04:04, Pat Riehecky wrote:
>>> On 01/04/2016 10:58 AM, Pat Riehecky wrote:
>>>> On 01/04/2016 10:30 AM, Steven Haigh wrote:
>>>>> On 05/01/16 03:27, Pat Riehecky wrote:
>>>>>> On 01/02/2016 12:49 AM, Steven Haigh wrote:
>>>>>>> Hi guys,
>>>>>>>
>>>>>>> Just wondering if it is possible to create an updates.img that
>>>>>>> includes
>>>>>>> the following kernel modules for the PXE boot install images:
>>>>>>>
>>>>>>> CONFIG_XEN_FBDEV_FRONTEND=m
>>>>>>> CONFIG_HVC_XEN=m
>>>>>>> CONFIG_HVC_XEN_FRONTEND=m
>>>>>>>
>>>>>>> The SL7 kernels used on the anaconda installer don't have these
>>>>>>> options
>>>>>>> set - so there is no VNC graphical output to the Xen system. This
>>>>>>> means
>>>>>>> that unless you use the 'console' (xl console command), then you
>>>>>>> can't
>>>>>>> see what's going on with the DomU install.
>>>>>>>
>>>>>>> It seems SL6 behaves properly for this - and it may well be seen to
>>>>>>> stray from the path too much to include in the base PXE image
>>>>>>> kernel -
>>>>>>> which means having an updates.img would be a nice compromise - ie
>>>>>>> its
>>>>>>> optional and doesn't require modification of the core install
>>>>>>> images.
>>>>>>>
>>>>>>> There is an updates.img currently in the PXE directory of
>>>>>>> 7rolling, but
>>>>>>> that seems to cause a whole heap of problems if its used...
>>>>>>>
>>>>>> Hi Steven,
>>>>>>
>>>>>> I've not got a lot of experience working with Xen, but I'll look into
>>>>>> what this would take.
>>>>> Thanks Pat,
>>>>>
>>>>> I know absolutely nothing about anaconda and the build process for
>>>>> images. I'd be more than happy to test whatever I can though.
>>>>>
>>>>> I run Xen just about everywhere - and also run http://xen.crc.id.au
>>>>> - so
>>>>> if you have any Xen questions, I'd be more than happy to help out.
>>>>>
>>>> I'm showing:
>>>>
>>>> $ grep CONFIG_HVC_XEN .config
>>>> CONFIG_HVC_XEN=y
>>>> CONFIG_HVC_XEN_FRONTEND=y
>>>>
>>>> for the 3.10.0-327 series kernels.
>>>
>>> Searching around upstream bugzilla, I'm not seeing any requests to get
>>> CONFIG_XEN_FBDEV_FRONTEND=m (or =y for that matter).
>>>
>>> Steven, can I have you file a bug upstream and put me on the CC list
>>> so we can get some forward motion on a long term solution?
>>
>> Hi Pat,
>>
>> I don't believe there is anything open in the RH BZ. The kernel config
>> has been the same through the EL7 betas up until current day - so I
>> believe putting a BZ report in would get a CLOSED WONTFIX.
>>
>> I'll quote a little bit of Konrad from CentOS fame from the EL7 betas:
>> ----- START QUOTE -----
>> You can boot an RHEL7 guest as PV, but there are issues:
>>
>>
>>   1). The FB driver has been unset (CONFIG_XEN_FBDEV_FRONTEND) that
>> means you can
>>       still do a text-console (in theory).
>>
>>
>>   2). The Xorg fb seems to suffer from some bug - which is why the Xen
>> FB has
>>       be turned off.
>>
>>
>>   3). There are also some systemd and udev things missing.
>>
>>
>> I understand that folks are interested in getting this fixed, but I was
>> wondering what the protocol is for getting said patches in the respective
>> RPMS (xorg-some-server, udev, systemd, kernel)?
>>
>>
>> Naturally this needs to be fixed upstream first, but once that has been
>> completed it should be fairly easy to backport it.
>> ----- END QUOTE -----
>>
>> From my experimentation, most of the above seems to be fixed. The one
>> problem is that because CONFIG_XEN_FBDEV_FRONTEND is not set for the
>> installer kernel, no FBDEV is initialised on installation - meaning
>> that if you use vncviewer to do the installation, you only get a
>> message saying "GUEST HAS NOT YET INITIALISED GRAPHICS".
>>
>> The text console is ONLY available by ssh'ing into the Xen Host and
>> using the 'xl console <guest name>' command. The vncviewer obviously
>> has the advantage that because its available over a network, no access
>> to the host is required to run the installer.
>>
>> I build a custom kernel for EL6 & EL7 that fixes this:
>>         http://xen.crc.id.au/git/?p=kernel-xen;a=summary
>>
>> It works perfectly for a both the Xen Guest (DomU) and Xen Host (Dom0)
>> - however trying to get this working on the installer is a bit of a
>> task beyond me.
>>
>> The thoughts behind specifically putting at least
>> CONFIG_XEN_FBDEV_FRONTEND as a module - then in an update image to be
>> provided to the installer via a kickstart wouldn't change any of the
>> current installer / code paths or vary from upstream.
>>
> 
> Hi Steven,
> 
> With RH suggesting HVM mode and (as expected) marking the upstream bug
> WONTFIX (BZ1296193), need to again show my ignorance on XEN. What is HVM
> mode?  Can it be a viable workaround?

Hi Pat,

Yeah - I figured that RH would close it as WONTFIX. It seems that
they're on a mission to make everyone do things their way and remove the
choice in OSS - but that's an entirely different topic for another time :)

Xen's types of virtualisation can be found here:
	http://wiki.xen.org/wiki/Xen_Project_Software_Overview#Guest_Types

In a nutshell, HVM is full system emulation complete with BIOS and
requires the VT-d in Intel CPUs (and whatever the equivalent is in AMD
land). PV is a more linux on linux solution that doesn't require any
special features.

As per the above URL (which explains the situation much better than I
could), the goal is to move towards PVH - however its not ready yet,
isn't widely deployed, and each time I've tried it, it doesn't actually
work.

As such, the current mass deployments of Xen anywhere other than AWS is
mostly PV - unless you have to run Windows - in which case you need HVM.

-- 
Steven Haigh

Email: [log in to unmask]
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897