[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] New to Xen: safety concerns (Linux Dom0, Windows DomU)
On Fri, Sep 9, 2011 at 1:41 PM, Drake Wilson <drake@xxxxxxxxxxxxxx> wrote: > One of your problems here is that VGA passthrough (at least if you want > it to hit the domU's BIOS) can actually be very hit-or-miss, though it's > gotten much better over time: > > http://wiki.xensource.com/xenwiki/XenVGAPassthrough Thanks, an excellent document. "Xen VGA graphics passthru is a special form of PCI passthru, and PCI passthru dedicates the PCI device (graphics card) to exactly one single VM." I assume I can switch it to a different VM on the fly? That is, boot with the graphics card dedicated to dom0 Linux, then fire up domU Windows and hand control over. > Can you describe which trouble you're worried about in particular, if any? Googling for 'xen uninstall' shows up a variety of people asking similar questions: http://forums.opensuse.org/english/get-technical-help-here/applications/418253-how-uninstall-xen.html - seems to have uninstalled cleanly http://www.linuxformat.com/forums/viewtopic.php?t=377 - not too clear on the question itself there http://ubuntuforums.org/archive/index.php/t-953793.html - required some manual cleanup and not sure if it really cleaned up (dated 2008) http://www.firewall.cx/ftopict-6304.html - no resolution, no responses at all (dated 2009) Not enough weight of evidence to turn me away from Xen, but enough to be concerned about. > Newer Linux kernels have Xen and non-Xen boot processes that are closer to > each other (I'm thinking 3.0.0 particularly; I don't know what Ubuntu 10.10 > has), According to `uname -a` it's currently 2.6.35-30-generic. I could upgrade the kernel to version 3 I guess, but I'm not a kernel expert so I'd be navigating unfamiliar waters. It'd be a separate "can I undo this if things go wrong" question all of its own. > and with things like UUID-based filesystem detection (which Ubuntu has > done as standard for a while, but not necessarily if you started from a much > older version) the differences in exposed hardware can often be automatically > dealt with. This particular box is quite new; 10.10 (I don't like 11.04) was installed fresh on a bare HD. It may have had a kernel upgrade or two but nothing particularly earth-shattering. > Older Linuxes had specialized Xen versions of the kernel, and > so you'd have to change boot configurations around more. In either case it'd > be > advisable to have a rescue disk handy just in case. But generally speaking > switching a Linux system between dom0 and raw is a very reversible operation > unless/until you configure it to depend strongly on Xen-specific or very > low-level > hardware operations. Thank you. I believe you, for I am sure you would not practice on my inexperience. I wish to do the right thing, and if - I say if - it really is that easy to reverse, the complexity shall be no obstacle to our union. Or something like that. (Pirates of Penzance, if you're not an opera buff.) >> 2) Can a DomU Windows have full access to the hardware? > > You should think about what you mean by "full access". You may be able to > pass > through most of the interface PCI devices and such (with work), but if you > will > still need access to the Linux half then you must arrange for enough console > or > network devices to be routed to it for that purpose. I want to play graphical Windows games. It's a 64-bit system with 8GB of RAM and a fairly new nVidia chipset video card (don't remember the spec atm), so in theory I should be able to give 2-3GB to a 32-bit WinXP and let that run happily, while leaving 5-6GB of real RAM for everything else. > Note also that you must have a hardware IOMMU for PCI passthrough to HVM > guests, > according to http://wiki.xensource.com/xenwiki/XenPCIpassthrough, and I don't > believe Windows can be run paravirtualized since the kernel hasn't been ported > (for obvious reasons). In practice this may mean some fairly high-class > hardware, > depending on your configuration. Hmm. Is there an easy way to check? It's a high-end Intel motherboard, and a high-end modern CPU, although I don't have the precise identifiers to hand. I'm not afraid of a bit of complexity, but my areas of expertise are user-level (ring 3) software and networking, not kernels and hypervisors. Much appreciate your help! Chris Angelico _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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