Hu Jia Yi
2007-Sep-07 04:08 UTC
[Xen-devel] Is it possible that Xen starts without Domain0
I have a question which may sound stupid.
Is the dom0 mainly responsible for administration of other VMs?
If a PC only needs running HVM and doesn''t need any administration, is
it possible that Xen doesn''t start dom0 but setup VM environment and
start-up HVM image?
What modification do I need, such as drivers, memory management, file
systems?
Best regards,
Hu Jia Yi
Ext: 20430
Tel: 65-67510430
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Today''s Topics:
1. Likely VMX Assist Issue from Ubuntu bug report (Zulauf, John)
2. Re: Likely VMX Assist Issue from Ubuntu bug report
(Mats Petersson)
3. Re: [VTD-NEO][patch 0/6] Intel VT-d/Neocleus 1:1 mreged code
for PCI passthrough (John Byrne)
4. RE: [VTD-NEO][patch 0/6] Intel VT-d/Neocleus 1:1 mreged code
for PCI passthrough (Kay, Allen M)
----------------------------------------------------------------------
Message: 1
Date: Thu, 6 Sep 2007 15:02:46 -0700
From: "Zulauf, John" <john.zulauf@intel.com>
Subject: [Xen-devel] Likely VMX Assist Issue from Ubuntu bug report
To: <xen-devel@lists.xensource.com>
Message-ID:
<BD262A443AD428499D90AF8368C4528DA20404@fmsmsx411.amr.corp.intel.com>
Content-Type: text/plain; charset="us-ascii"
"fancy isolinux screen on install isos hang xen/kvm HVM guests"
https://bugs.launchpad.net/ubuntu/+bug/83642
Bug is in state "confirmed" and while the concensus on the bug thread
is
"we probably shouldn''t be doing fancy things in protected
mode", this
seems like a fairly important distro to be borked for 3.2 (or 3.1.1
whatever).
I''ve verified this using the i386 Ubuntu tip:
http://cdimage.ubuntu.com/releases/gutsy/tribe-5/gutsy-desktop-i386.iso
FYI
John Zulauf
Quoting the Ubuntu bug:
I''m working with ubuntu on Xen right now, and this is a very bad
problem. Both the server and desktop install CD''s, for both dapper and
edgy, use fancy full screen (vbe based?) isolinux install screens. Could
we please do away with these screens on the server or alternate install
CD? These fancy screens are causing fully virtualized guests that try to
boot from these CD''s to crash before the boot screen is even drawn.
This
is true for both Xen and KVM.
To clarify, this does not cause the -host- to crash, just the guest, but
you get a blank screen and wonder what happened.
Background (mostly speculation, but I think it''s right):
Intel designed VT in a strange way, such that only protected mode
instructions are allowed o be virtualized. Anything done in real mode
must be emulated...every instruction. The Xen and KVM folks have
emulated enough to get things working, but have not handled every
instruction, including apparently some of the fancy (VBE?) graphics
isolinux on the ubuntu boot cd''s is using. (FreeBSD''s btx
loader also
has problems)
For reference, AMD''s SVM analogue does, in fact, virtualize real mode
instructions on the processor, and I''m able to boot all install
CD''s
just fine on an AMD machine. This is an Intel VT .... ''quirk''.
The mini.iso network install CD loads just fine and works, and I can
install over an emulated network. And that CD includes a splash screen
w/ isolinux, so it''s not all VBE operations that cause problems. You
should still be able to have a splash screen, but more then that might
cause the problems.
I''ve filed a bug against Xen about this, and I just tried KVM and ran
into the same issue, so I''m assuming it''s th same problem. But
until the
Xen folks figure out what instructions need to be emulated, and take
enough time to care, or Intel comes out with an updated VT
implementation that does what AMD''s does, we can''t just boot
up a ubuntu
install CD on virtual machines and have it work.
My requested solution is that isolinux use just the standard (preferably
text) menu and options on the server and/or alternate install CD. Having
one full, officially supported install CD that doesn''t crash Xen/KVM
when trying to install a ubuntu would go a long way towards helping
those of us trying to use ubuntu in a virtual environment out. Besides,
while I really appreciate all the fancy boot options for a desktop
machine, but I would prefer a plain text option for servers anyway. I
do, however, see why some would like the opposite.
Would it be possible to get the feisty ''server'' install CD to
forgo the
fancy bootup options?
NOTE: I think I understand what''s going on, but if I''m missing
something
obvious, please tell me.
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Message: 2
Date: Thu, 06 Sep 2007 23:13:37 +0100
From: Mats Petersson <mats@planetcatfish.com>
Subject: Re: [Xen-devel] Likely VMX Assist Issue from Ubuntu bug
report
To: "Zulauf, John"
<john.zulauf@intel.com>,<xen-devel@lists.xensource.com>
Message-ID: <46e07b6e.1185300a.4139.05c4@mx.google.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 23:02 06/09/2007, Zulauf, John wrote:>Content-class: urn:content-classes:message
>Content-Type: multipart/alternative;
> boundary="----_=_NextPart_001_01C7F0D1.A664E607"
>
>"fancy isolinux screen on install isos hang xen/kvm HVM guests"
>
><https://bugs.launchpad.net/ubuntu/+bug/83642>https://bugs.launchpad.ne
t/ubuntu/+bug/83642>
>Bug is in state "confirmed" and while the concensus on the bug
>thread is "we probably shouldn''t be doing fancy things in
protected
>mode", this seems like a fairly important distro to be borked for
>3.2 (or 3.1.1 whatever).
>
>I''ve verified this using the i386 Ubuntu tip:
><http://cdimage.ubuntu.com/releases/gutsy/tribe-5/gutsy-desktop-i386.is
o>http://cdimage.ubuntu.com/releases/gutsy/tribe-5/gutsy-desktop-i386.is
o
As far as I know, this is still the case. And the reason is, as
stated in the bug-report, that the Intel people decided to not allow
real-mode code to be virtualized. This is not a problem in itself,
because VM8086 mode can cover most of the code, with a bit of
"VMXAssist" to fix up privileged instructions not allows in VM8086
mode. However, there is a problem, and that is that the state of
segment registers isn''t maintained when switching from protected mode
back to real-mode. This is often used by boot-loading code to load
data into memory that is normally not reachable from real-mode (that
is, memory above 1M).
--
Mats
>
>FYI
>
>John Zulauf
>
>Quoting the Ubuntu bug:
>
>I''m working with ubuntu on Xen right now, and this is a very bad
>problem. Both the server and desktop install CD''s, for both dapper
>and edgy, use fancy full screen (vbe based?) isolinux install
>screens. Could we please do away with these screens on the server or
>alternate install CD? These fancy screens are causing fully
>virtualized guests that try to boot from these CD''s to crash before
>the boot screen is even drawn. This is true for both Xen and KVM.
>
>To clarify, this does not cause the -host- to crash, just the guest,
>but you get a blank screen and wonder what happened.
>
>Background (mostly speculation, but I think it''s right):
>Intel designed VT in a strange way, such that only protected mode
>instructions are allowed o be virtualized. Anything done in real
>mode must be emulated...every instruction. The Xen and KVM folks
>have emulated enough to get things working, but have not handled
>every instruction, including apparently some of the fancy (VBE?)
>graphics isolinux on the ubuntu boot cd''s is using.
(FreeBSD''s btx
>loader also has problems)
>
>For reference, AMD''s SVM analogue does, in fact, virtualize real
>mode instructions on the processor, and I''m able to boot all
install
>CD''s just fine on an AMD machine. This is an Intel VT ....
''quirk''.
>
>The mini.iso network install CD loads just fine and works, and I can
>install over an emulated network. And that CD includes a splash
>screen w/ isolinux, so it''s not all VBE operations that cause
>problems. You should still be able to have a splash screen, but more
>then that might cause the problems.
>
>I''ve filed a bug against Xen about this, and I just tried KVM and
>ran into the same issue, so I''m assuming it''s th same
problem. But
>until the Xen folks figure out what instructions need to be
>emulated, and take enough time to care, or Intel comes out with an
>updated VT implementation that does what AMD''s does, we
can''t just
>boot up a ubuntu install CD on virtual machines and have it work.
>
>My requested solution is that isolinux use just the standard
>(preferably text) menu and options on the server and/or alternate
>install CD. Having one full, officially supported install CD that
>doesn''t crash Xen/KVM when trying to install a ubuntu would go a
>long way towards helping those of us trying to use ubuntu in a
>virtual environment out. Besides, while I really appreciate all the
>fancy boot options for a desktop machine, but I would prefer a plain
>text option for servers anyway. I do, however, see why some would
>like the opposite.
>
>Would it be possible to get the feisty ''server'' install CD
to forgo
>the fancy bootup options?
>
>NOTE: I think I understand what''s going on, but if I''m
missing
>something obvious, please tell me.
>
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@lists.xensource.com
>http://lists.xensource.com/xen-devel
------------------------------
Message: 3
Date: Thu, 06 Sep 2007 16:16:29 -0700
From: John Byrne <john.l.byrne@hp.com>
Subject: Re: [Xen-devel] [VTD-NEO][patch 0/6] Intel VT-d/Neocleus 1:1
mreged code for PCI passthrough
To: "Kay, Allen M" <allen.m.kay@intel.com>
Cc: Guy Zana <guy@neocleus.com>, xen-devel@lists.xensource.com, Keir
Fraser <keir@xensource.com>
Message-ID: <46E08A4D.8050706@hp.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
When I use these patches and start a nativedom with a directly-assigned
NIC and no IOMMU, I get a lock up. Running the same
domain/configuration/machine with the direct-io.hg tree worked fine. The
crash output is below. If you''d like more information, let me know.
John Byrne
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) pt_irq.c:81:d1 invalid assert_option value
(XEN) WARNING: send pio with something already pending (9)?
(XEN) domain_crash_sync called from hvm.c:485
(XEN) Domain 1 (vcpu#0) crashed on cpu#7:
(XEN) ----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----
(XEN) CPU: 7
(XEN) EIP: 0000:[<00100fcb>]
(XEN) EFLAGS: 00000002 CONTEXT: hvm
(XEN) eax: 00000064 ebx: 001390c4 ecx: 001390c4 edx: 000000e9
(XEN) esi: 00103762 edi: 00101bf0 ebp: 00139038 esp: 00139038
(XEN) cr0: 00000011 cr4: 00000000 cr3: 00000000 cr2: 00000000
(XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: 0000
(XEN) domain_crash_sync called from hvm.c:132
(XEN) domain_crash_sync called from hvm.c:132
(XEN) domain_crash_sync called from hvm.c:132
(XEN) domain_crash_sync called from hvm.c:132
....
(XEN) *** [ Xen-3.0-unstable x86_32 debug=n Not tainted ]----(XEN)
----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----(XEN) e
x86_32 debug=n Not tainted ]----
(XEN) ----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----
(XEN) CPU: 6
(XEN) CPU: 6(XEN) idle_loop+0x1b/0x90+010246 CONTEXT: hypervisor
(XEN) EFLAGS: 00010246 CONTEXT: hypervisor
(XEN) eax: 00000300 ebx: ffbe7fb4 ecx: 00000000 edx: 00000006
(XEN) esi: ff1a8430 edi: 91d91b27 ebp: 0000001c esp: ffbe7fa8
(XEN) cr0: 8005003b cr4: 000026d0 cr3: 3c6ee000 cr2: b7bf7000
(XEN) ds: e010 es: e010 fs: 0000 gs: 0000 ss: e010 cs: e008
(XEN) do_page_fault+0x45/0x3b0
(XEN) (XEN) Xen stac00010246Xen stac00010246
CR3: 00000000(XEN) ffbea080
ax: 6563696c ebx: 0000e010 ecx: 00010246 edx: ff1b7fb4(XEN)
ffbea080 00000001
si: 0000e010 edi: 00000000 ebp: ff1b40ec esp: ff1b40a8(XEN)
00000000
s: e010 es: e010 fs: 0000 gs: 0000 ss: e010(XEN) c1351f90
00000006 00000006
00000006
(XEN) c03d7180 00000000 000e0007 c01013a7 00000061 00000246 c1351f8c
00000069
(XEN) 0000007b 0000007b 00000000 00000000 00000006 ffbea080
(XEN) Xen call trace:
(XEN) [<ff1209fb>] idle_loop+0x1b/0x90
(XEN)
Kay, Allen M wrote:> The following 6 patches contains merge of Intel VT-d and Neocleus''
1:1
> mapping patches for enabling HVM guest direct device access that were
> last submitted around end of May. These patches applied cleanly to
> changeset 15730.
>
> To enabled xen vt-d code, add "ioapic_ack=old" to xen boot
parameter
in> grub.conf on systems with VT-d hardware.
>
> To enabled xen 1:1 mapping code, add "enabled_nativedom=1" to xen
boot
> parameter in grub.conf.
>
> Signed-off-by: Allen Kay <allen.m.kay@intel.com>
> Signed-off-by: Guy Zana <guy@neocleus.com>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
------------------------------
Message: 4
Date: Thu, 6 Sep 2007 17:00:31 -0700
From: "Kay, Allen M" <allen.m.kay@intel.com>
Subject: RE: [Xen-devel] [VTD-NEO][patch 0/6] Intel VT-d/Neocleus 1:1
mreged code for PCI passthrough
To: "John Byrne" <john.l.byrne@hp.com>
Cc: Guy Zana <guy@neocleus.com>, xen-devel@lists.xensource.com, Keir
Fraser <keir@xensource.com>
Message-ID:
<13A2F7DE1BAEA345A61DD40F303ED7A66C5CF9@scsmsx412.amr.corp.intel.com>
Content-Type: text/plain; charset="us-ascii"
Other than minor changes while rebasing from 15521 to 15730. The
following files have been modified that might affect functionality:
Tools/hvmloader/32bitbios_support.c:
removed a hack to increase highbiosarea size.
Tools/ioemu/hw/pass-throught.c/pt_pci_write_config():
for is_native=1 case, pass-through pci config writes. Otherwise,
pass-through only access to command register (for vt-d case). Note that
we will use a different switch variable once it is added.
These are minor changes, you might want to replace these file from the
ones from direct-io tree to see if it fixes your problem.
Allen
>-----Original Message-----
>From: John Byrne [mailto:john.l.byrne@hp.com]
>Sent: Thursday, September 06, 2007 4:16 PM
>To: Kay, Allen M
>Cc: xen-devel@lists.xensource.com; Guy Zana; Keir Fraser
>Subject: Re: [Xen-devel] [VTD-NEO][patch 0/6] Intel
>VT-d/Neocleus 1:1 mreged code for PCI passthrough
>
>When I use these patches and start a nativedom with a
>directly-assigned
>NIC and no IOMMU, I get a lock up. Running the same
>domain/configuration/machine with the direct-io.hg tree worked
>fine. The
>crash output is below. If you''d like more information, let me know.
>
>John Byrne
>
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) pt_irq.c:81:d1 invalid assert_option value
>(XEN) WARNING: send pio with something already pending (9)?
>(XEN) domain_crash_sync called from hvm.c:485
>(XEN) Domain 1 (vcpu#0) crashed on cpu#7:
>(XEN) ----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----
>(XEN) CPU: 7
>(XEN) EIP: 0000:[<00100fcb>]
>(XEN) EFLAGS: 00000002 CONTEXT: hvm
>(XEN) eax: 00000064 ebx: 001390c4 ecx: 001390c4 edx: 000000e9
>(XEN) esi: 00103762 edi: 00101bf0 ebp: 00139038 esp: 00139038
>(XEN) cr0: 00000011 cr4: 00000000 cr3: 00000000 cr2: 00000000
>(XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: 0000
>(XEN) domain_crash_sync called from hvm.c:132
>(XEN) domain_crash_sync called from hvm.c:132
>(XEN) domain_crash_sync called from hvm.c:132
>(XEN) domain_crash_sync called from hvm.c:132
>....
>(XEN) *** [ Xen-3.0-unstable x86_32 debug=n Not tainted ]----(XEN)
>----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----(XEN) e
>x86_32 debug=n Not tainted ]----
>(XEN) ----[ Xen-3.0-unstable x86_32 debug=n Not tainted ]----
>(XEN) CPU: 6
>(XEN) CPU: 6(XEN) idle_loop+0x1b/0x90+010246 CONTEXT: hypervisor
>
>(XEN) EFLAGS: 00010246 CONTEXT: hypervisor
>(XEN) eax: 00000300 ebx: ffbe7fb4 ecx: 00000000 edx: 00000006
>(XEN) esi: ff1a8430 edi: 91d91b27 ebp: 0000001c esp: ffbe7fa8
>(XEN) cr0: 8005003b cr4: 000026d0 cr3: 3c6ee000 cr2: b7bf7000
>(XEN) ds: e010 es: e010 fs: 0000 gs: 0000 ss: e010 cs: e008
>(XEN) do_page_fault+0x45/0x3b0
>(XEN) (XEN) Xen stac00010246Xen stac00010246
>CR3: 00000000(XEN) ffbea080
> ax: 6563696c ebx: 0000e010 ecx: 00010246 edx: ff1b7fb4(XEN)
>ffbea080 00000001
> si: 0000e010 edi: 00000000 ebp: ff1b40ec esp: ff1b40a8(XEN)
>00000000
> s: e010 es: e010 fs: 0000 gs: 0000 ss: e010(XEN) c1351f90
>00000006 00000006
> 00000006
>(XEN) c03d7180 00000000 000e0007 c01013a7 00000061 00000246
>c1351f8c
>00000069
>(XEN) 0000007b 0000007b 00000000 00000000 00000006 ffbea080
>(XEN) Xen call trace:
>(XEN) [<ff1209fb>] idle_loop+0x1b/0x90
>(XEN)
>
>
>Kay, Allen M wrote:
>> The following 6 patches contains merge of Intel VT-d and
>Neocleus'' 1:1
>> mapping patches for enabling HVM guest direct device access that were
>> last submitted around end of May. These patches applied cleanly to
>> changeset 15730.
>>
>> To enabled xen vt-d code, add "ioapic_ack=old" to xen boot
>parameter in
>> grub.conf on systems with VT-d hardware.
>>
>> To enabled xen 1:1 mapping code, add "enabled_nativedom=1"
>to xen boot
>> parameter in grub.conf.
>>
>> Signed-off-by: Allen Kay <allen.m.kay@intel.com>
>> Signed-off-by: Guy Zana <guy@neocleus.com>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>>
>
------------------------------
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
End of Xen-devel Digest, Vol 31, Issue 26
*****************************************
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pradeep singh rautela
2007-Sep-07 04:18 UTC
Re: [Xen-devel] Is it possible that Xen starts without Domain0
On 9/7/07, Hu Jia Yi <jyhu@asmpt.com> wrote:> I have a question which may sound stupid. > > Is the dom0 mainly responsible for administration of other VMs? > If a PC only needs running HVM and doesn''t need any administration, is > it possible that Xen doesn''t start dom0 but setup VM environment and > start-up HVM image?I am not sure if that is possible, but i doubt possible atleast right now. hypervisor itself is pretty thin and minimal and does not contain most of the drivers.Directly booting a HVM(e.g a linux kernel on XYZ distro) means giving hardware control to that HVM drivers which is not something intended. What happens if there are two HVM? Thanks --psr> > What modification do I need, such as drivers, memory management, file > systems? > > Best regards, > Hu Jia Yi > Ext: 20430 > Tel: 65-67510430 >-- -- pradeep singh rautela "question = ( to ) ? be : ! be;" -- Wm. Shakespeare _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hu Jia Yi
2007-Sep-07 04:34 UTC
RE: [Xen-devel] Is it possible that Xen starts without Domain0
Hi, Dom0 itself is a virtual domain. I think the function of HVM should not depend on the dom0. So the question is if without any interference from dom0, how Xen helps HVM to function, such as creating a virtual disk for HVM, PCI, VGA, etc. Does this need modification of xen? Best regards, Hu Jia Yi Ext: 20430 Tel: 65-67510430 -----Original Message----- From: pradeep singh rautela [mailto:rautelap@gmail.com] Sent: Friday, September 07, 2007 12:18 PM To: Hu Jia Yi Cc: xen-devel Subject: Re: [Xen-devel] Is it possible that Xen starts without Domain0 On 9/7/07, Hu Jia Yi <jyhu@asmpt.com> wrote:> I have a question which may sound stupid. > > Is the dom0 mainly responsible for administration of other VMs? > If a PC only needs running HVM and doesn''t need any administration, is > it possible that Xen doesn''t start dom0 but setup VM environment and > start-up HVM image?I am not sure if that is possible, but i doubt possible atleast right now. hypervisor itself is pretty thin and minimal and does not contain most of the drivers.Directly booting a HVM(e.g a linux kernel on XYZ distro) means giving hardware control to that HVM drivers which is not something intended. What happens if there are two HVM? Thanks --psr> > What modification do I need, such as drivers, memory management, file > systems? > > Best regards, > Hu Jia Yi > Ext: 20430 > Tel: 65-67510430 >-- -- pradeep singh rautela "question = ( to ) ? be : ! be;" -- Wm. Shakespeare _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
pradeep singh rautela
2007-Sep-07 04:43 UTC
Re: [Xen-devel] Is it possible that Xen starts without Domain0
On 9/7/07, Hu Jia Yi <jyhu@asmpt.com> wrote:> Hi, > > Dom0 itself is a virtual domain. I think the function of HVM should notyes it is but it is a special domain which enjoys priviliges like creating and controling other domUs and direct access to hardware through device drivers. In short hypervisor trusts dom0 and grants exclusive hardware access to it.> depend > on the dom0. So the question is if without any interference from dom0, > how Xen > helps HVM to function, such as creating a virtual disk for HVM, PCI, > VGA, etc.But still someone need to communicate with the actual hardware devices. Who will do it then if there is no privileged domain which is trusted by hypervisor? All the preliminary setup a HVM needs is done by the dom0. In short yes you may need heavy modifications to the hypervisor if you want HVM to directly boot without any dom0. And i guess that would mean moving a lot of stuff from dom0 to hypervisor just to make sure a HVM boots directly :-/. Too much of overkill i think. May be somebody else(Keir, Matt??) explain it in a correct way. Thanks --psr> > Does this need modification of xen? > > Best regards, > Hu Jia Yi > Ext: 20430 > Tel: 65-67510430 > > -----Original Message----- > From: pradeep singh rautela [mailto:rautelap@gmail.com] > Sent: Friday, September 07, 2007 12:18 PM > To: Hu Jia Yi > Cc: xen-devel > Subject: Re: [Xen-devel] Is it possible that Xen starts without Domain0 > > On 9/7/07, Hu Jia Yi <jyhu@asmpt.com> wrote: > > I have a question which may sound stupid. > > > > Is the dom0 mainly responsible for administration of other VMs? > > If a PC only needs running HVM and doesn''t need any administration, is > > it possible that Xen doesn''t start dom0 but setup VM environment and > > start-up HVM image? > I am not sure if that is possible, but i doubt possible atleast right > now. > hypervisor itself is pretty thin and minimal and does not contain most > of the drivers.Directly booting a HVM(e.g a linux kernel on XYZ > distro) means giving hardware control to that HVM drivers which is not > something intended. What happens if there are two HVM? > > Thanks > --psr > > > > What modification do I need, such as drivers, memory management, file > > systems? > > > > Best regards, > > Hu Jia Yi > > Ext: 20430 > > Tel: 65-67510430 > > > > > -- > -- > pradeep singh rautela > > "question = ( to ) ? be : ! be;" > -- Wm. Shakespeare >-- -- pradeep singh rautela "question = ( to ) ? be : ! be;" -- Wm. Shakespeare _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2007-Sep-07 07:33 UTC
Re: [Xen-devel] Is it possible that Xen starts without Domain0
On 7/9/07 05:08, "Hu Jia Yi" <jyhu@asmpt.com> wrote:> I have a question which may sound stupid. > > Is the dom0 mainly responsible for administration of other VMs? > If a PC only needs running HVM and doesn''t need any administration, is > it possible that Xen doesn''t start dom0 but setup VM environment and > start-up HVM image?dom0 manages I/O devices (network, disk, video, ...) and also runs support services (driver backends, device emulation) for PV and HVM guests. A Xen system will definitely not work without dom0. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel