Xen project Mailing List

Hello Jason,

Looking at your configuration, was the kernel built to be PV Compatible (http://sanifool.wordpress.com/2013/01/09/booting-up-a-domu-on-xen-4-2/).

The disk line looks fine provided you wanted to pass the whole disk to your PVM (including it's partition table etc). ÂAlso if you have it mounted while trying to launch the PVM that may throw warnings or errors.

Is it possible you are missing the bootloader (http://xenbits.xen.org/docs/4.2-testing/man/xl.cfg.5.html)?

I don't believe it would affect your ability to launch the PVM, but the I am unfamiliar with your vif device model, and the mac address isn't in the suggested Xen range (http://xenbits.xen.org/docs/4.2-testing/misc/xl-network-configuration.html).

If you are looking for more detailed diagnostics, you might check that the xen-debug kernel flag is set (and rebuild your ramdisk or kernel).

Logging must vary by distribution as I almost never see non-kernel software log its errors to dmesg (/var/log/messages), but most will place logs into the same directory and organize them by file or folder. ÂIn Xen's case it uses your toolstacks command xl dmesg (/var/logs/xen/).

---

On Thu, Feb 21, 2013 at 2:24 PM, Jason Vas Dias <jason.vas.dias@xxxxxxxxx> wrote:

I'm beginning to conclude that Xen is not of sufficient code quality
to be useful.

Firstly, Âmy 'xl create' command returns a 0 exit status, meaning
success, but yet no domain
is created or can be attached to or listed with 'xl list' :

# xl create my_domain.cfg
Parsing config from my_domain.cfg
Daemon running with PID 1436
# echo $?
0
# xl list
Name Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ÂID Â Mem VCPUs Â Â ÂState Â Time(s)
Domain-0 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0 Â1024 Â Â 2 Â Â r----- Â Â Â35.5

This appears to be due to this error message in 'xl dmesg' output :

(XEN) Dom5 may compromise security on this CPU.
(XEN) traps.c:2584:d5 Domain attempted WRMSR 00000000c0010004 from
0x0000000000000000 to 0x000000000000abcd.

>From reading the source, the traps.c message appears to indicate an
error condition, but you would not know this from the log message.

Have you checked all of the log files in /var/logs/xen/?

Pretty sure that so long as the configuration itself doesn't contain syntactical errors and the command to qemu goes through that xl will assume it did its job.

Is it possible xl create is launching the domains just fine (hence code 0), and they are failing at a different stage (eg qemu during boot due to configuration problems)?

Anyone know how to avoid this unhandled WRMSR ?

Code that silently ignores and does not report error conditions does
not get my vote of confidence.

Can anyone convince me that Xen is of sufficient quality to be used ?

Plenty of well known companies are using Xen, but I don't believe they are using the very latest stable release (4.2.1). ÂAFAIK 4.2.1 is not available as a package in any stable operating systems yet. ÂStable release of code does notÂguaranteeÂit will be compatible without plenty of configuration based on your choice of Dom0.

However I am under the assumption that you are not using it for production purposes given your choices (Xen 4.2.1 and ArchLinux don't exactly point to concerns with stability or desirable ease of operation as a priority). ÂIf that is the case then as a personal user I can say that I have had great success using Xen 4.2 on Debain Wheezy for several months now. ÂHowever I have not dabbled in many of the areas you are (such as iSCSI, PVM's and programmatic domain control).

However, even with my limited experience, I can easily conclude that because Xen can be used for such a wide variety of purposes it becomes that much harder to ensure functionality as factors that can influence success tend to cover a wide range (host hardware, Xen version, installed packages and package versions, Dom0 distro and version, etc).

Hope these answers will help you identify the problem.

~Casey

Re: [Xen-users] help please - running a guest from an iSCSI disk ? getting more diagnostics than "cannot make domain: -3" ? how to make domain0 "privileged" ?