Xen users - Feb 2008 - Fwd: Re: Xen 3.1, Fedora 8 and PCI passthrough

----------  Forwarded Message  ----------

Subject: Re: [Xen-users] Xen 3.1, Fedora 8 and PCI passthrough
Date: Sunday 24 February 2008
From: jim burns <jim_burn@bellsouth.net>
To: deshantm@gmail.com

On Friday 22 February 2008 09:34:17 pm Todd Deshane
wrote:
> The configuration in both python and SXP format is covered in the xen user
> manual [0].
>
> Fedora still does make a config file, I don''t have a system on
hand to
> check the location of it.
>
> According to this post [1] there are in /var/lib/xend/domains
>
> [0]
> http://www.cl.cam.ac.uk/research/srg/netos/xen/readmes/user/user.html#SECTI
>ON03230000000000000000 [1]
> http://forums.fedoraforum.org/showthread.php?t=179944
I''ve never found a flat config file on fedora, after using
virt-manager.
Here''s an example of a dumpxml file, and then the flat config file I
created
from it. Just remove any references to the currently running vm, like the 
domain id, pty, etc. from the xml file, and put the flat config file 
in /etc/xen (otherwise you need to specify the complete path to
''xm''.

xml:

<domain type=''xen''>
  <name>fc8</name>
  <uuid>10461fc0-adac-ef4b-e6d6-b27d95ac9b24</uuid>
  <bootloader>/usr/bin/pygrub</bootloader>
  <os>
    <type>linux</type>
  </os>
  <memory>524288</memory>
  <vcpu>1</vcpu>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <interface type=''bridge''>
      <mac address=''00:16:3e:1f:12:dd''/>
      <script path=''vif-bridge''/>
    </interface>
    <disk type=''file'' device=''disk''>
      <driver name=''tap'' type=''aio''/>
      <source file=''/var/lib/xen/images/fc8''/>
      <target dev=''xvda''/>
    </disk>
    <graphics type=''vnc'' port=''-1''
keymap=''en-us'' />
    <console protocol=''vt100'' />
  </devices>
</domain>

and flat config:

name=''fc8''
memory=512
uuid=''10461fc0-adac-ef4b-e6d6-b27d95ac9b24''
bootloader=''/usr/bin/pygrub''
on_poweroff=''destroy''
on_reboot=''restart''
on_crash=''restart''
vcpu=1
disk=[ ''tap:aio:/var/lib/xen/images/fc8,xvda,w'' ]
vif=[ ''mac=00:16:3e:1f:12:dd'' ]
vfb=[ ''type=vnc, keymap=en-us, vnclisten=0.0.0.0, vncunused=1''
]
vncconsole=1
stdvga=1
usbdevice=''tablet''
extra = ''xencons=tty''

The stdvga parm will give you 640x480, besides the normal 800x600. The 
usbdevice parm needs to be supplemented by the instructions in the xen docs 
mentioned above, in the section ''A.4.3 Mouse issues, especially under
VNC''. I
find the method that worked for me was the ''USB tablet over USB
port.'' one.
It tells you to go to another url for the general download and config 
instructions, but to replace part of the xorg.conf in the domu with the 
stanza given in the xen docs. I found that even after this change, I still 
had to change the MaxX and MaxY parms to match the *current* resolution in 
the domu, which means that every time you change the resolution, you have to 
change MaxX/Y. Also, the ''Identifier      "Tablet"''
statement has to be
changed to ''Identifier      "touchscreen"''. Good
luck.

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Hello everybody, thank you very much for your help so far.

Only config file (in Fedora 8)  I´ve found is located in 
/var/lib/xend/domains/UUID/config.sxp

To get the NIC found in geust I added the following text

(device
    (pci
        (dev
            (domain 0)
            (bus 04)
            (slot 00)
        )
    )
)

After I have started the guest once the text i rewritten like this:
    (device
        ((uuid 8b227afe-1b04-ab6a-4071-21d53dfb4254)
            (dev (slot 00) (bus 04) (domain 0))
        )
    )

If I do a dumpxml I get the following:
<domain type=''xen'' id=''1''>
  <name>Test</name>
  <uuid>9a795b3f-21cc-4b63-9399-c86aca5ad6ba</uuid>
  <bootloader>/usr/bin/pygrub</bootloader>
  <os>
    <type>linux</type>
  </os>
  <memory>524288</memory>
  <vcpu>1</vcpu>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <interface type=''bridge''>
      <source bridge=''eth1''/>
      <target dev=''vif1.0''/>
      <mac address=''00:16:3e:60:78:57''/>
      <script path=''vif-bridge''/>
    </interface>
    <disk type=''file'' device=''disk''>
      <driver name=''file''/>
      <source file=''/home/xen/test.img''/>
      <target dev=''xvda''/>
    </disk>
    <input type=''mouse'' bus=''xen''/>
    <graphics type=''vnc'' port=''5900''/>
    <console tty=''/dev/pts/3''/>
  </devices>
</domain>

The interface section is as I understand wrong because the guest is now 
using the PCI NIC directly, not via a bridge.

If I try to shutdown the guest it never stops, in virt-manager it says 
Running and if i try in virsh shutdown test it says Domain test is being 
shutdown.

If I now restart the computer and then open virt-manager my test domain 
is nowhere to be found. I have to edit the config.sxp file and remove 
the section about the NIC. I insert my own text and then my domain is 
back again. Is there a way to find out what the problem might be?


Kenneth Lundström





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On Monday 25 February 2008 10:48:42 am Kenneth Lundström
wrote:
> If I now restart the computer and then open virt-manager my test domain
> is nowhere to be found. I have to edit the config.sxp file and remove
> the section about the NIC. I insert my own text and then my domain is
> back again. Is there a way to find out what the problem might be?
It''s probably not a great idea to edit the UUID/config.sxp, and
definitely not
when the guest is running. This points out the different styles virt-manager 
and the usual ''xm'' usage employ. When you create a domain in
virt-manager /
virt-install, it does the equivalent of a ''virsh define
xmlfile'', which
creates your UUID/config.sxp. Then to start the guest, the gui does the 
equivalent of ''virsh start domain-name(as defined in the xml
file)''. When you
shutdown, virt-manager still has the definition until you do a ''virsh 
undefine ...''. (The corresponding xm commands are xm new, xm start, and
xm
delete.)

The user who uses xm instead of a gui typically uses xm create, and xm destroy 
or shutdown (or shuts down gracefully from within the guest), which leaves no 
residual trace of the domain in the xenstore databases. It''s always a
good
idea to have copies of the dumpxml, or the flat config you created from it, 
in case the xenstore definitions disappear, or are corrupted (in which case 
you erase /var/lib/xend/domains/UUID after rebooting into a non-xen kernel).

The difference between the dumpxml and the flat config is which command you 
create the domain with. virsh define/create uses xml, xm new/create uses the 
flat config. I personally always create a domain from a config, which is 
backed up along with everything else important, and don''t worry about
whether
xen will remember my domain''s definition w/o corruption in
it''s database.
Also, having a config you can edit allows you to add more advanced features 
(like pci passthrough) that the gui can''t handle. Editing a database
is,
again, probably a bad idea.

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On Monday 25 February 2008 10:48:42 am Kenneth Lundström
wrote:
> Kenneth Lundström
Then, after you have added all the advanced features you want to your xml or 
flat config file, and you have tested them out with xm/virsh create, if you 
prefer using a gui, then you can shutdown the guest, do a ''virsh define
xml-config'' or ''xm new flat-config'', and voila! - You
can use the gui
(virt-manager) again.

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