Trouble making a Xen Host (Dom0)

locerra · n00b Joined: 20 Feb 2011 Posts: 12 Location: Seattle

Hi,

So I've been trying to make a gentoo xen host of and on for a little while now, and I can't seem to resolve the issue I'm having. When trying to boot into the system, it crashes upon starting init. More specifically, I have two entries in my Grub2 configuration, one which loads the xen stuff before my initrd, and the other that just uses my initrd. When preloading the xen stuff, it crashes after it completes my initrd (and reboots the system).

Versions of the relevant software: gentoo-sources-3.2.12, xen-tools-4.1.1-r6, xen-4.1.1-r2, grub-2.00-beta3-r2.
I followed the guide on the gentoo wiki http://en.gentoo-wiki.com/wiki/Xen4.1, but I have no idea it is crashing on me.

Any help would be much appreciated, let me know if I can provide any more details (my configurations are pretty bare bone though, since this is a clean install based off of the guide).

Thanks

Mad Merlin · Veteran Joined: 09 May 2005 Posts: 1134

Any reason you want Xen specifically? I would recommend KVM for new installs, it's much nicer to work with.
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locerra · n00b Joined: 20 Feb 2011 Posts: 12 Location: Seattle

Well, I chose Xen over kvm because as far as I'm aware kvm doesn't support dynamic cpu management nor graphics passthrough. Also, how is kvm's memory ballooning, it is still marked as experimental in the kernel config. If my knowledge is dated, then I would have no problem using kvm.

Mad Merlin · Veteran Joined: 09 May 2005 Posts: 1134

By dynamic cpu management, do you mean cpu hotplug? If so, KVM has had it for a long time. KVM supports PCIe passthrough with the right hardware support (VT-d), though it can be hit and miss, based on the motherboard BIOS and/or the actual expansion card. I have seen successful reports with GPU passthrough through. Memory ballooning I believe is pretty mature now, though I've never tried it myself.
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cach0rr0 · Posted: Fri May 04, 2012 2:56 am Post subject:

two things:

-i second the comments about KVM, and yes, PCI passthrough works, as does cpu hotplugging
-if you want to diagnose the Xen crash, id be curious to know that the text of the "crash" actually says. May be the case you fare better making your own initramfs.
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locerra · n00b Joined: 20 Feb 2011 Posts: 12 Location: Seattle

Ok, I'll see if I can get what I want set up with KVM, although I'm sceptical about of the status graphics passthrough (there seems to be very limited success from what I've read).

As for the crash, it prints nothing. What I get is the expected xen.gz stuff, then my initramfs stuff, then it tells me init is starting, a moment or two passes and it reboots.