Mailing List Archive

> When Dom0 is kind of a VM, then Xen Hypervisor running in a VM???
XEN is the hypervisor, some kind of micro-kernel, which boots first
(type I hypervisor). Then comes the dom0 kernel, be it Linux or NetBSD.
XEN tools are the userland utilities to control the hypervisor from
within the dom0. Yes, the "control domain" or the "service console", as
VMware used to call it at some time, is indeed some kind of a VM, but it
has access to network and disk devices, to then share those to the
unprivileged guests (domU).

When you setup a bootloader manually (ideally MULTIBOOT2 capable), it
becomes perfectly clear. Try to have a look at your boot-loader setup,
you will see something gets loaded before the main system kernel.

HTH
--
Pierre-Philipp Braun
SMTP Health Campaign: enforce STARTTLS and verify MX certificates
<https://nethence.com/smtp/>

Hello,Is Dom0 part of the Xen hypervisor or is the OS?

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On Tue, Jul 20, 2021 at 7:29 PM, Pierre-Philipp Braun<pbraun@nethence.com> wrote: > When Dom0 is kind of a VM, then Xen Hypervisor running in a VM???
XEN is the hypervisor, some kind of micro-kernel, which boots first
(type I hypervisor).  Then comes the dom0 kernel, be it Linux or NetBSD.
  XEN tools are the userland utilities to control the hypervisor from
within the dom0.  Yes, the "control domain" or the "service console", as
VMware used to call it at some time, is indeed some kind of a VM, but it
has access to network and disk devices, to then share those to the
unprivileged guests (domU).

When you setup a bootloader manually (ideally MULTIBOOT2 capable), it
becomes perfectly clear.  Try to have a look at your boot-loader setup,
you will see something gets loaded before the main system kernel.

HTH
--
Pierre-Philipp Braun
SMTP Health Campaign: enforce STARTTLS and verify MX certificates
<https://nethence.com/smtp/>

On 20/07/2021 17:37, Jason Long wrote:
> Hello,
> Is Dom0 part of the Xen hypervisor or is the OS?

It's the OS plus some tools (xen-tools). I suggest you experiment more
with Community XEN and all those things will clarify by themselves.

--
Pierre-Philipp Braun
SMTP Health Campaign: enforce STARTTLS and verify MX certificates
<https://nethence.com/smtp/>

Thanks.Thus, Xen installed on the Dom0?

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On Tue, Jul 20, 2021 at 8:17 PM, Pierre-Philipp Braun<pbraun@nethence.com> wrote: On 20/07/2021 17:37, Jason Long wrote:
> Hello,
> Is Dom0 part of the Xen hypervisor or is the OS?

It's the OS plus some tools (xen-tools).  I suggest you experiment more
with Community XEN and all those things will clarify by themselves.

--
Pierre-Philipp Braun
SMTP Health Campaign: enforce STARTTLS and verify MX certificates
<https://nethence.com/smtp/>

Hello,

On Tue, Jul 20, 2021 at 08:21:51PM +0000, Jason Long wrote:
> Thus, Xen installed on the Dom0?

The Xen hypervisor kernel image is usually stored inside what is the
dom0's /boot directory but it is booted directly by the
hardware/firmware before dom0 exists, because dom0 is just another
VM that the hypervisor then runs.

The image also might not be stored inside the dom0 filesystem as it
might be booted over the network or whatever.

Also a full Xen install is not functional without its management
tools, of which the dom0 operating system and several software
packages on it are a part.

So whether you consider Xen to be installed "on" the dom0 is really
a question of perspective. You aren't asking specific enough
questions to get a simple short answer.

Cheers,
Andy

Thank you Andy.
Thus, Xen Hypervisor runs directly on the hardware without any OS? If yes, after it, the Dom0 (an Operating System) run as a VM by Xen Hypervisor?






On Wednesday, July 21, 2021, 04:14:43 AM GMT+4:30, Andy Smith <andy@strugglers.net> wrote:





Hello,

On Tue, Jul 20, 2021 at 08:21:51PM +0000, Jason Long wrote:
> Thus, Xen installed on the Dom0?


The Xen hypervisor kernel image is usually stored inside what is the
dom0's /boot directory but it is booted directly by the
hardware/firmware before dom0 exists, because dom0 is just another
VM that the hypervisor then runs.

The image also might not be stored inside the dom0 filesystem as it
might be booted over the network or whatever.

Also a full Xen install is not functional without its management
tools, of which the dom0 operating system and several software
packages on it are a part.

So whether you consider Xen to be installed "on" the dom0 is really
a question of perspective. You aren't asking specific enough
questions to get a simple short answer.

Cheers,
Andy

Just to add to the discussion, there is also the possiility of runing Xen
without the dom0.
http://xenbits.xen.org/docs/unstable/features/dom0less.html


Atenciosamente,
*Charles Ferreira Gonçalves *




On Wed, Jul 21, 2021 at 9:31 AM Jason Long <hack3rcon@yahoo.com> wrote:

> Thank you Andy.
> Thus, Xen Hypervisor runs directly on the hardware without any OS? If yes,
> after it, the Dom0 (an Operating System) run as a VM by Xen Hypervisor?
>
>
>
>
>
>
> On Wednesday, July 21, 2021, 04:14:43 AM GMT+4:30, Andy Smith <
> andy@strugglers.net> wrote:
>
>
>
>
>
> Hello,
>
> On Tue, Jul 20, 2021 at 08:21:51PM +0000, Jason Long wrote:
> > Thus, Xen installed on the Dom0?
>
>
> The Xen hypervisor kernel image is usually stored inside what is the
> dom0's /boot directory but it is booted directly by the
> hardware/firmware before dom0 exists, because dom0 is just another
> VM that the hypervisor then runs.
>
> The image also might not be stored inside the dom0 filesystem as it
> might be booted over the network or whatever.
>
> Also a full Xen install is not functional without its management
> tools, of which the dom0 operating system and several software
> packages on it are a part.
>
> So whether you consider Xen to be installed "on" the dom0 is really
> a question of perspective. You aren't asking specific enough
> questions to get a simple short answer.
>
> Cheers,
> Andy
>
>
>
>