RE: [Xen-users] Firewire, PCI TV Tuner Card, PCI Wireless LAN Card, and USB Device Support Under Windows XP Xen Guest

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: Teo En Ming [mailto:space.time.universe@xxxxxxxxx] 
> Sent: 22 May 2007 16:39
> To: Petersson, Mats
> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Firewire, PCI TV Tuner Card, PCI 
> Wireless LAN Card, and USB Device Support Under Windows XP Xen Guest
> 
> Another thing to worry about is harddisk access speed in 
> Windows guests. Video editing requires fast harddisk access 
> speeds. I could give the virtual machine lots of ram if I 
> have lots of physical memory to spare, so memory requirements 
> is not much of an issue in a windows guest. Unless memory 
> access is slower than native in a windows guest. 

The hard-disk speed should be reasonably equal to real hardware if you
use para-virtual drivers (such as using XenExpress or any other
"commercial" product that is supplying the same fucntionality).
Para-virtual drivers stop the drive from being "emulated hardware", but
instead feed the disk-IO directly to Dom0 in one simple packet, which is
much better than about 5-6 transitions between Dom0 and the guest before
a single disk-IO is emulated in the basic system. 

Memory should be very close to the native speed. There is a difference
in handling the page-table, but I would expect a video editing software
to attempt to avoid page-table operation in native mode (as they are
somewhat slow in native mode too, even if they are x times faster than
the virtualized version). 

> 
> 
> On 5/22/07, Teo En Ming <space.time.universe@xxxxxxxxx> wrote:
> 
>       Oh dear, I've let the video card requirement in Windows 
> guests slipped my mind. If I remember correctly, the virtual 
> video card in Windows guest is somewhat backward/obsolete, 
> and may not work with video editing software. Even if video 
> editing software can be successfully installed in a windows 
> guest, it may refuse to run/start due to an obsolete virtual 
> video card. 
>       
>       Based on the same principle as AGP and PCI, I won't be 
> able to use PCI Express x16 video cards in Windows guests too.

Yes, PCI-e is also a PCI architecture from a software and most hardware
standpoints - only the actual signalling between one point of hardware
and another is (very) different from other PCI architectures [and, for
completeness, from a software standpoint, there is some support for
extended registers - but that's not really important here]. 

--
Mats
>       
>       Sigh...
>       
>       
>       
>       On 5/22/07, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> 
> 
> 
>               > -----Original Message-----
>               > From: Teo En Ming 
> [mailto:space.time.universe@xxxxxxxxx ]
>               > Sent: 22 May 2007 15:55
>               > To: Petersson, Mats
>               > Cc: xen-users@xxxxxxxxxxxxxxxxxxx
>               > Subject: Re: [Xen-users] Firewire, PCI TV 
> Tuner Card, PCI
>               > Wireless LAN Card, and USB Device Support 
> Under Windows XP Xen Guest 
>               >
>               > Hi
>               >
>               > Thank you for your reply.
>               >
>               > May I know when will IOMMU hardware be 
> arriving? Any specific
>               > roadmap/dates?
>               
>               I don't work for the right part of AMD to know 
> the planned (or actual) 
>               release-dates of new products, and I don't 
> quite know which product(s)
>               the IOMMU will go into. It's not going to 
> happen in the next few weeks,
>               I can assure you of that, but as I said, I 
> don't really know much about 
>               which parts will come out when - I usually know 
> that some new product
>               has been released when it's announced by e-mail 
> to all AMDers.
>               >
>               > I think I will still be going for current 
> virtualization
>               > processors. I will still be able to install 
> video editing 
>               > software inside Windows XP guests and do all 
> my video editing
>               > there, while I will move all other computing 
> activities to my
>               > linux host operating system.
>               
>               Yes, as far as I can determine, there's nothing 
> in Video editing that 
>               would be hardware specific, so it should work 
> just fine in a virtual
>               Windows system. [Although if the graphics 
> requirements are high for the
>               video editing software, you may still need to 
> use a dedicated machine 
>               for that, rather than a virtual machine, simply 
> to get the graphics
>               performance].
>               >
>               > Will I be able to play Windows-based PC games 
> inside Windows guests?
>               
>               Short answer: No.
>               Long answer: Yes, as long as they don't require 
> high-end 3D graphics. 
>               You can't use 3D graphics cards for the same 
> reason as any other PCI
>               device (AGP8x is PCI from software and most 
> hardware standpoints, it's
>               just a different connector and somewhat 
> different clock and signaling). 
>               
>               --
>               Mats
>               >
>               >
>               >
>               > On 5/22/07, Petersson, Mats < Mats.Petersson@xxxxxxx 
>               > <mailto:Mats.Petersson@xxxxxxx > > wrote:
>               >
>               >
>               >
>               >       > -----Original Message-----
>               >       > From: 
> xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> <mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx> 
>               >       > [mailto: 
> xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
>               >       > Teo En Ming
>               >       > Sent: 22 May 2007 14:44 
>               >       > To: xen-users@xxxxxxxxxxxxxxxxxxx 
> <mailto:xen-users@xxxxxxxxxxxxxxxxxxx> 
>               >       > Subject: [Xen-users] Firewire, PCI TV 
> Tuner Card, PCI
>               >       > Wireless LAN Card, and USB Device 
> Support Under
>               > Windows XP Xen Guest
>               >       > 
>               >       > Dear All,
>               >       >
>               >       > Assuming that I buy a HVM compatible 
> processor and
>               >       > motherboard, and having installed a 
> linux host operating
>               >       > system with a Xen kernel, I proceed 
> to install a Windows XP 
>               >       > guest virtual machine. The question is:
>               >       >
>               >       > Will I be able to use the firewire 
> ports, USB ports, TV Tuner
>               >       > program and wireless LAN card inside 
> Windows XP guest VM? 
>               >
>               >       Nope, none of these devices (aside from 
> limited USB
>               > support, possibly),
>               >       will work under Xen, since (at present) 
> there is no support to
>               >       hide/assign PCI devices to the HVM 
> domain. This in turn 
>               > is because of
>               >       the fact that PCI devices access memory 
> directly, which
>               > isn't going to
>               >       work when Xen has told "lies" [1] to 
> the Windows guest
>               > about where the 
>               >       memory is. So when the guest OS tells 
> the PCI device
>               > where in memory
>               >       something is, it will not know that 
> this is not the
>               > ACTUAL physical
>               >       address. And there's no easy way to 
> solve this in software only. 
>               >
>               >       In future generations of 
> processors/chipsets, there
>               > will be IOMMU
>               >       hardware that allows us to redirect the 
> memory requests from a
>               >       particular PCI device, so that we can 
> continue to hide 
>               > the ACTUAL
>               >       physical address and still use the PCI 
> devices within a
>               > guest. But
>               >       that's a little way out at this time.
>               >
>               >
>               >       [1] All operating systems want memory 
> to start at 
>               > address zero. Since
>               >       only one CAN have this address, guests 
> in HVM-mode will
>               > get a fake
>               >       memory map that starts at zero and goes 
> to whatever
>               > size it's configured
>               >       to. The fact that the ACTUAL physical 
> address of the 
>               > guest's memory is
>               >       somewhere else is completely hidden 
> from the guest by
>               > using either
>               >       shadow-paging or hardware assisted 
> paging (AMD Nested
>               > paging or Intel's
>               >       corresponding technology) [once this 
> technology reaches
>               > customers,
>               >       sometime later this year or so].
>               >
>               >
>               >       > Will I be able to do video editing 
> inside Windows XP guest 
>               >       > VM? Or is networking the one and only 
> feature that is
>               >       > supported under Windows XP guest 
> operating system? And I
>               >       > won't be able to use anything else 
> inside Windows XP guest? 
>               >
>               >       You should be able to edit video in the 
> guest, as long
>               > as you don't rely
>               >       on hardware features in PCI devices to do this.
>               >
>               >       Likewise, I don't see why you need to 
> use Windows to 
>               > connect to the
>               >       Wireless network, you can just as well 
> hide the fact
>               > that it's wireless
>               >       from Windows, and just use virtual 
> network device, and
>               > use the Linux
>               >       bridge setting to connect it to the 
> physical Wireless device. 
>               >
>               >       But you are correct, that the current 
> technology only
>               > allows a limited
>               >       set of hardware features within the 
> guest. This is a hardware
>               >       restriction, and it's nothing to do 
> with Xen in itsels, 
>               > but with the
>               >       current state of hardware. Future generations of
>               > hardware will remove
>               >       some or all of these restrictions (but 
> leaving one remaining
>               >       restriction: each guest will HAVE to 
> have it's own 
>               > hardware to access -
>               >       no sharing of a single device without 
> interfacing
>               > through a virtual
>               >       device - this is because all OS's 
> requires that the
>               > hardware they
>               >       control is their own. There are 
> hardware devices (such 
>               > as network cards)
>               >       that support "multi-access" by 
> providing multiple
>               > device-instances.
>               >       These of course can be shared, as they 
> are from a
>               > software standpoint
>               >       multiple devices, and each device will 
> thus have it's
>               > sole owner).
>               >
>               >       --
>               >       Mats
>               >       >
>               >       > Thank you.
>               >       >
>               >       > 
>               >
>               >
>               >
>               >
>               >
>               >
>               
>               
>               
> 
> 
> 
> 



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