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FS#33061 - x86_64 does not boot under Xen with vcpus greater than 1

Attached to Project: Arch Linux
Opened by Daniel Shub (daniel_shub) - Wednesday, 12 December 2012, 10:30 GMT
Last edited by Dave Reisner (falconindy) - Saturday, 15 December 2012, 19:47 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Gerardo Exequiel Pozzi (djgera)
Architecture All
Severity Critical
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No


The Arch cd iso installer does not load the x86_64 system when trying to create a Xen HVM domU when the vcpus is greater than 1. I cannot copy the error, but it basically says:

Cannot get hvm parameter 18: -22!
BUG: scheduling while atomic: swapper/1/0/0x000000002
bad: scheduling from the idle thread!

I described the problem on the forum and someone else has experienced the same problem:

Additional info:
* package version(s)
* config and/or log files etc.

I am using the 2012.12.01 cd iso, and my dom0 is running 64-bit Debian Squeeze, Xen version 4.0, and Linux Kernel 2.6.32. I am using an Intel i7 processor.

Steps to reproduce:

Create a Xen dom0. Create an HVM domU with the following configuration file

kernel = '/usr/lib/xen-4.1/boot/hvmloader'
builder = 'hvm'
memory = '2048'
name = 'arch'
disk = [

Click on the x86_64 installer from the iso. Everything works if vcpus is equal to 1.
This task depends upon

Closed by  Dave Reisner (falconindy)
Saturday, 15 December 2012, 19:47 GMT
Reason for closing:  Upstream
Additional comments about closing:  Upstream problem with Xen (and perhaps less likely, linux itself).
Comment by Alexander F Rødseth (xyproto) (trontonic) - Saturday, 15 December 2012, 16:35 GMT
djgera, hope it's ok that I assigned this one to you
Comment by Dave Reisner (falconindy) - Saturday, 15 December 2012, 16:38 GMT
I can't possibly see how this is something we can fix in Arch. Why not report this to Xen developers?
Comment by Alexander F Rødseth (xyproto) (trontonic) - Saturday, 15 December 2012, 16:40 GMT
Good point, Dave.

Daniel, please report the bug upstream to the Xen developers:

Thanks for reporting.
Comment by Mark Hurenkamp (hurenkam) - Saturday, 15 December 2012, 19:41 GMT
Although it could be a xen problem, i think it is more likely to be a kernel problem, as i've described in the thread mentioned in the report.
So far, Arch is the only OS i encountered that exposes this problem. All other distro's i've tried so far (successfully), have had kerenels <= 3.5,
and usually their own set of patches.
I suggest giving a vanilla 3.6 kernel a try, if that runs fine, then it is at least related to Arch patches, if not, then it is an upstream kernel and/or xen problem.
Note that passing 'debug' on the kernel command line also fixes the problem (kernel boots fine then with 8 vcpus)
Comment by Dave Reisner (falconindy) - Saturday, 15 December 2012, 19:46 GMT