[Fedora-xen] General confusion

[Gerhardus Geldenhuis]

Hi
My goal is to create a xen domain using lvm backed storage. It sounds simple
and probably is but I am getting caught down in the details. I am using RH5
which I am hopefull will be similar enough to be able to ask on this list.
Its the only list on https://www.redhat.com/mailman/listinfo with xen in the
name.

Up to now I have been using virt-install to create new domains. It takes
care of a lot of detail but this is a lot like spoon feeding and you learn
nothing plus it is limited in capabilities at the moment.

Confusion one:
When creating a new domain it creates a config file that xm can use:
name = "test03"
uuid = "80bd6bda-c559-3a68-643c-df0f29d672b9"
maxmem = 200
memory = 200
vcpus = 1
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [  ]
disk = [ "tap:aio:/root/temppart/test03.img,xvda,w" ]
vif = [ "mac=00:16:3e:24:15:79,bridge=virbr0" ]

When I dump the config using virsh it adds some additinal paramters:

  <os>
    <type>linux</type>
    <kernel>/var/lib/xen/boot_kernel.nNlfNC</kernel>
    <initrd>/var/lib/xen/boot_ramdisk.jV4otH</initrd>
    <cmdline>ro root=/dev/VolGroup00/LogVol00 console=xvc0</cmdline>

This names changes every time you restart the xen domain. What creates this
<random> kernel and initrd and would using the following config be the same
thing:

    <kernel>/boot/vmlinuz-2.6.18-53.el5xen</kernel>
    <initrd>/boot/initrd-2.6.18-53.el5xen.img</initrd>

I am also a bit confused about the <cmdline> value and how it is used and
what it should be. If anybody has a brief explanation of how this fits into
the greater scheme of things it would be really appreciated.

Lastly, I have managed to create a xml config file for virsh which does not
immediatly complain about any errors. However I am still unsure how/where to
specify the installation (http) source. I dont want to copy a existing
installation I want to create a new one, would this just be a kernel
parameter?

The config file I am using:
<domain type='xen' id='3'>
  <name>test-a-01</name>
  <os>
    <type>linux</type>
    <kernel>/boot/vmlinuz-2.6.18-53.el5xen</kernel>
    <initrd>/boot/initrd-2.6.18-53.el5xen.img</initrd>
    <cmdline>ro root=/dev/VolGroup00/LogVol00 console=xvc0</cmdline>
  </os>
  <memory>202144</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='virbr0'/>
      <script path='vif-bridge'/>
    </interface>
    <disk type='phy' device='disk'>
      <driver name='tap' type='aio'/>
      <source file='/root/parts/test-a-01.img'/>
      <target dev='xvda'/>
    </disk>
    <console tty='/dev/pts/2'/>
  </devices>
</domain>


Regards

-- 
Gerhardus Geldenhuis
Registered Linux User #193352
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