Hello, I got into a debate about if xen is really a type 1 hypervisor. A friend said that Xen/KVM/Intel are not really type 1 hypervisor, that is, the "real" type 1 hypervisor is the one running with Sparc. (?) How to know? Because if you reboot the Host, vm''s keep running, that means, it''s type 1. (?) -- At this point, I am confused. Is he talking about HVM? Is he mixing HVM with type 1? What I know it''s what wikipedia and other xen related documents say about type 1, that is, the hypervisor is at the lowest level, next to the hardware, and controlled at an upper level by dom0. He also says that there are not many differences between type 1 and type 2 in practice, when talking about the xen and kvm model as wikipedia describes it. What do you think? Is he mistaken? Thanks _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Hello Eva,
I would consider Xen to be a type 1 Hypervisor, it runs directly on the
hardware and manages resources.
Your friend may be misunderstanding Dom0 as a "host", but Dom0 is just
a
privileged control OS running ontop of the hypervisor ("second layer"
if
going by the description).
I tried ESXi, and switched to Xen specifically because the tiny built-in
control OS doesn''t support a myriad of consumer drivers, something that
having a Linux control guest fixes.
http://www.virtuatopia.com/images/0/0f/Hypervisor_diagram.jpg
On Mon, Apr 16, 2012 at 5:57 AM, eva <evammg@gmail.com> wrote:
> Hello,
>
>
> I got into a debate about if xen is really a type 1 hypervisor. A friend
> said that Xen/KVM/Intel are not really type 1 hypervisor, that is, the
> "real" type 1 hypervisor is the one running with Sparc. (?)
>
>
> How to know? Because if you reboot the Host, vm''s keep running,
that
> means, it''s type 1. (?)
>
>
> -- At this point, I am confused. Is he talking about HVM? Is he mixing HVM
> with type 1?
>
>
> What I know it''s what wikipedia and other xen related documents
say about
> type 1, that is, the hypervisor is at the lowest level, next to the
> hardware, and controlled at an upper level by dom0.
>
>
> He also says that there are not many differences between type 1 and type 2
> in practice, when talking about the xen and kvm model as wikipedia
> describes it.
>
>
> What do you think? Is he mistaken?
>
>
> Thanks
>
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xen.org
> http://lists.xen.org/xen-users
>
_______________________________________________
Xen-users mailing list
Xen-users@lists.xen.org
http://lists.xen.org/xen-users
On 16 April 2012 13:57, John McDermott CIV <john.mcdermott@nrl.navy.mil> wrote:> > > The main Wikipedia article is not clear. Type 1 and Type 2 are NOT defined by what is "running" on what. All of the software "runs" on the hardware. The meaning of Type 1 and Type 2 depends on what is called a _sensitive instruction_: any instruction in the hardware ISA that could interfere with or screw up the hypervisor. A hypervisor needs to control and manage the execution of all sensitive instructions, so it needs to know when a guest is attempting to execute a sensitive instruction, and take control. Otherwise, a guest could misuse a sensitive instruction. An example of a sensitive instruction on the x86 is int n. > > A Type 1 hypervisor detects sensitive instructions for itself but a Type 2 hypervisor relies on some other software (typically a conventional OS)to detect them and then pass the notification on to the hypervisor. > > Xen is Type 1; you can look at the source code to confirm this, though you will need to understand how to read AT&T assembler syntax. > > Sincerely, > > John > >John, Clear enough :) Thank you. Casey, Could you explain this "I tried ESXi, and switched to Xen specifically because the tiny built-in control OS doesn''t support a myriad of consumer drivers, something that having a Linux control guest fixes." in a different way?
On Mon, Apr 16, 2012 at 7:47 AM, eva <evammg@gmail.com> wrote:> Could you explain this > > "I tried ESXi, and switched to Xen specifically because the tiny > built-in control OS doesn''t support a myriad of consumer drivers, > something that having a Linux control guest fixes." > > in a different way?altought Xen itself manages CPU, VM switches, RAM, PCI access, and a few other things; other, more ''external'' hardware (mainly block and network devices) is managed by Dom0 processes. There you benefit from the wide hardware support of Linux, in contrast to the small selection of drivers available to VMWare -- Javier
Thanks Javier, that was much clearer than what I was about to send. ESXi has a tiny control OS, which while lighter weight only targets server grade components. In my situation my consumer motherboard (ASRock Z68 Extreme7 Gen3) has a Broadcom BCM57781 Dual LAN adapter, and ESXi did not have that driver so the system simply didn''t work. Simple answer, lacks driver flexibility. On Mon, Apr 16, 2012 at 10:24 AM, Javier Guerra Giraldez <javier@guerrag.com> wrote:> On Mon, Apr 16, 2012 at 7:47 AM, eva <evammg@gmail.com> wrote: > > Could you explain this > > > > "I tried ESXi, and switched to Xen specifically because the tiny > > built-in control OS doesn''t support a myriad of consumer drivers, > > something that having a Linux control guest fixes." > > > > in a different way? > > > altought Xen itself manages CPU, VM switches, RAM, PCI access, and a > few other things; other, more ''external'' hardware (mainly block and > network devices) is managed by Dom0 processes. There you benefit from > the wide hardware support of Linux, in contrast to the small selection > of drivers available to VMWare > > > -- > Javier >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
On 16 April 2012 16:33, Casey DeLorme <cdelorme@gmail.com> wrote:> Thanks Javier, that was much clearer than what I was about to send. > > ESXi has a tiny control OS, which while lighter weight only targets server > grade components. > > In my situation my consumer motherboard (ASRock Z68 Extreme7 Gen3) has a > Broadcom BCM57781 Dual LAN adapter, and ESXi did not have that driver so the > system simply didn''t work. > > Simple answer, lacks driver flexibility.Sorry for my ignorance. But I thought ESXi was based on RedHat, ..so I thought it could benefit itself from the drivers that Linux uses, because is Red Hat (?)
On Mon, Apr 16, 2012 at 10:12 AM, eva <evammg@gmail.com> wrote:> Sorry for my ignorance. But I thought ESXi was based on RedHat, ..so I > thought it could benefit itself from the drivers that Linux uses, > because is Red Hat (?)there''s not much information about how close to Linux is the control system of VMWare. there has been some accusations of GPL noncompliance, after all. but still, i guess they heavily modify the kernel and drivers, so they only maintain a very small subset of them. -- Javier
---------- Forwarded message ---------- From: Javier Guerra Giraldez <javier@guerrag.com> Date: 16 April 2012 17:50 Subject: Re: [Xen-users] Is Xen really a Type 1 Hypervisor? To: eva <evammg@gmail.com> Cc: Casey DeLorme <cdelorme@gmail.com>, John McDermott CIV <john.mcdermott@nrl.navy.mil>, xen-users@lists.xen.org On Mon, Apr 16, 2012 at 10:12 AM, eva <evammg@gmail.com> wrote:> Sorry for my ignorance. But I thought ESXi was based on RedHat, ..so I > thought it could benefit itself from the drivers that Linux uses, > because is Red Hat (?)there''s not much information about how close to Linux is the control system of VMWare. there has been some accusations of GPL noncompliance, after all. but still, i guess they heavily modify the kernel and drivers, so they only maintain a very small subset of them. --- Javier, I see. I had no idea about the driver issue with vmware.. Always the same old story with open source software.. Anyways, It''s been all very clarifying. Thank you!!
While Xen is indeed actually a Type 1 hypervisor, confusion is understandable. With VMware ESXi, another Type 1 hypervisor, you install ESXi on a machine using an ESXi install disk. And then ESXi runs on that machine, hosting whatever guest operating systems you install on it. You manage the hypervisor over the network from another machine, which may be running Windows, running the vSphere Client. VMware used to make a Type 2 hypervisor called VMware GSX Server, which ran on top of a server operating system, and which could therefore be managed from the keyboard and screen of the server itself. When you install Xen, though, you use a Linux install disk. After you have installed Linux, you add a Xen package which both puts Xen administration tools in the copy of Linux you have installed, and installs Xen itself as another operating system. Then you use GRUB to switch things around so that Xen boots up, but it still subsequently starts that copy of Linux as a special guest operating system with the power to administer Xen. So it''s a Type 1 hypervisor that does a good job of appearing like a Type 2 hypervisor if you don''t pay attention to what''s going on technically behind the scenes. You install Linux, then you boot into the Linux that you installed to control the hypervisor - just as you would have if it were Type 2. -- View this message in context: http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5712507.html Sent from the Xen - User mailing list archive at Nabble.com.
On 11/20/2012 10:03 PM, quadibloc wrote:> While Xen is indeed actually a Type 1 hypervisor, confusion is > understandable. > > With VMware ESXi, another Type 1 hypervisor, you install ESXi on a machine > using an ESXi install disk. And then ESXi runs on that machine, hosting > whatever guest operating systems you install on it. You manage the > hypervisor over the network from another machine, which may be running > Windows, running the vSphere Client. > > VMware used to make a Type 2 hypervisor called VMware GSX Server, which ran > on top of a server operating system, and which could therefore be managed > from the keyboard and screen of the server itself. > > When you install Xen, though, you use a Linux install disk. After you have > installed Linux, you add a Xen package which both puts Xen administration > tools in the copy of Linux you have installed, and installs Xen itself as > another operating system. Then you use GRUB to switch things around so that > Xen boots up, but it still subsequently starts that copy of Linux as a > special guest operating system with the power to administer Xen. > > So it''s a Type 1 hypervisor that does a good job of appearing like a Type 2 > hypervisor if you don''t pay attention to what''s going on technically behind > the scenes. You install Linux, then you boot into the Linux that you > installed to control the hypervisor - just as you would have if it were Type > 2. > > -- > View this message in context: http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5712507.html > Sent from the Xen - User mailing list archive at Nabble.com. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users >Hi quadibloc, Xen definitely is type1 hypervisor. You have to differentiate between Xen hypervisor and dom0 management domain. In VMware ESX you have both hypervisor and management stack in one ''package'', but in Xen it''s not. Xen has separate small-size hypervisor running directly on top of HW and dom0 is started just on top of it. dom0 is communicating via special communication channels with Xen hypervisor and providing only management stack. Therefore the dom0 kernel needs to be patched to support this communication channels and it could be GNU/Linux or NetBSD or any other system you would like to patch to support Xen management. Xen''s advantage of ESX is that it doesn''t need to ''support'' the HW it is running on. The HW needs to be supported only by dom0. For better understanding read this: http://wiki.xen.org/wiki/Xen_Overview and continue with http://wiki.xen.org/wiki/Xen_Beginners_Guide . Best regards, -- Peter Viskup
As of ESXI VMware stoped using RedHat for the management console VM. They say now that the management is inbeded into the hypervisor and it''s based on BusyBox. -- View this message in context: http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5720205.html Sent from the Xen - User mailing list archive at Nabble.com.
On Mon, Dec 02, 2013 at 02:50:27PM -0800, RKDTOO wrote:> As of ESXI VMware stoped using RedHat for the management console VM. They say > now that the management is inbeded into the hypervisor and it''s based on > BusyBox. >Sorry I am not able to get what you mean. I think you can easily find the definition of type 1 hypervisor on Wikipedia.org. http://en.wikipedia.org/wiki/Hypervisor Wei.> > > -- > View this message in context: http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5720205.html > Sent from the Xen - User mailing list archive at Nabble.com. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users
On Tue, 2013-12-03 at 12:16 +0000, Wei Liu wrote:> On Mon, Dec 02, 2013 at 02:50:27PM -0800, RKDTOO wrote: > > As of ESXI VMware stoped using RedHat for the management console VM. They say > > now that the management is inbeded into the hypervisor and it''s based on > > BusyBox. > > > > Sorry I am not able to get what you mean. I think you can easily find > the definition of type 1 hypervisor on Wikipedia.org. > > http://en.wikipedia.org/wiki/HypervisorThis thread is more than a year old, I don''t think there is any need to revive it here, it is barely on topic IMHO. Ian.
My apologies; I was merely commenting on this post <http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5644651.html> . Not many people know that the new ESXi (not ESX) console is based on BusyBox, not RedHat. -- View this message in context: http://xen.1045712.n5.nabble.com/Is-Xen-really-a-Type-1-Hypervisor-tp5643400p5720212.html Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users