Re: [Xen-users] Separate kernel on domU's

[eva <evammg@xxxxxxxxx>]

Hello,

On 22 February 2012 14:12, Qrux <qrux.qed@xxxxxxxxx> wrote:
>
> On Feb 22, 2012, at 3:28 AM, eva wrote:
>
>> Hello,
>>
>> I am still learning about Xen.. I am trying to setup Xen hypervisor
>> for the first time. I was reading the howto here:
>>
>> http://www.howtoforge.com/paravirtualization-with-xen-4.0-on-debian-squeeze-amd64
>
> If I were you, I would use a commercial distro (e.g., openSUSE) to learn 
> about Xen.  It's the most robust and mature experience, and has the least 
> amount of tinkering with stuff like custom kernels.
>

Maybe I should've said that I have been working with Debian for
years.. I prefer Debian, although this is my first time learning about
virtualization.. always handled virtualization thru a GUI, so never
learned how it really works..

>> "(To use the default Ubuntu kernel instead of Debian's Xen kernel in
>> the guest, you can also comment out the kernel and initrd lines in
>> /etc/xen-tools/xen-tools.conf.)"
>
> If you don't understand what you're reading here, that's another sign that 
> it's probably more productive to use a commercial distro that offers Xen. 
>  You seem new...So, the information I'm giving you is at a more basic level 
> than maybe some of the other responses you've gotten.
>

I prefer to learn! I am not scared! :D

>> Also, I have read about the stub domains to load a separate kernel.
>>
>> At this point I am a bit lost.
>>
>> I have searched information about this but it's still not clear to me.
>>
>> It seems that Xen hypervisor shares the kernel with domU's, but this
>> is not recommended because it makes it can easily mess it all up..
>> But, with an option through xen-tools you can create a domU with a
>> separate kernel.. does that mean that uses a stub domain?
>
> Xen is a Type-1 hypervisor.  It doesn't really "share the kernel" with 
> anything.

It seems I need to study a bit more about the general background of
virtualization. That's what I'll do.

>
> It *is* a kernel...though, from your perspective, it's a bit more like a 
> super-fancy boot-loader.
>
> After Xen itself (the bare-metal hypervisor) boots, it will then load the 
> domU kernel.  At that point, it transfer "control over to the dom0 
> kernel--otherwise known as your "Host" OS.  The general process is:
>
>        1. You load Xen on the hardware (usually via a Grub entry).
>        2. Xen loads your dom0 (usually via that same Grub entry).
>        3. Then, you load domUs on your dom0 (through interacting with Xen 
> from dom0).
>
> You'll use your Host OS and the Xen tools it provides (which communicate to 
> the Hypervisor sitting under the host), you'll create domUs (Guest OSes). 
>  Those domUs can be of all different types, and which you specifically 
> need...Is determined by what you need it for--or, what your boss/client 
> needs.  A variety of different OSes can be used as Xen Guest OSes.
>
> Each DomU has it's own separate kernel.  You can choose to use the dom0 
> kernel (it's just a file, from Xen's perspective), but that's just a 
> coincidence.  It makes sense conceptually to think of domUs having their own 
> kernels.  In the configuration for each Guest, you'll specific a file on the 
> dom0 filesystem which will be the kernel of the Guest.  Guests can use the 
> same file, but each Guest will load that kernel as a separate instance. 
>  Don't confuse pointing to the FILE that is a kernel in a Guest config with 
> "sharing a running kernel".
>
> I hope this information can help you get started.
>
>        Q
>

Ok, I need some time to study this a bit more and I'll give you a feed back.

Thank you guys!

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
http://lists.xen.org/xen-users