Re: [Xen-devel] xen 4.0.1 w/2.6.32.47 hangs at boot

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Wed, Dec 14, 2011 at 10:05:36PM +0100, Quartexx wrote:
> 2011/12/14 Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>:
> > I would hazzard a guess that it is something with the 3ware driver.
> > Can you configure Alt-SysRq so that you can see the stack trace of
> > dom0 and where it hanged? And also do Ctrl-Ax3 and press 'q' to see
> > where dom0 is stuck? It should print out a bunch of 0xff.. and I can
> > help you debug what that is in the dom0 kernel so we can figure out
> > what is happening.
> 
> 
> Thanks, I would try that as soon as possible (unfortunately this box
> is in a remote datacenter)

Ok, but you have a serial console, so you should be able to trigger
Alt-SysRQ using the serial console. I think it is something like 'send
break'. You should Google for it thought.

> Googling I found this
> https://bugzilla.redhat.com/show_bug.cgi?id=429937
> They suggest to rebuild initrd including scsi_wait_scan module.

Well, you are not even seeing the "Booting has failed" and I did not see
anything in your serial log saying that it had gone further in the boot
to start the initrd process.

You could expand the boot process by adding 'initcall_debug' to give a
better idea where it is in the boot process.
> Another workaround could be to use rootdelay in the kernel command line
> Worth a try or a waste of time?
> 
> 
> > Or you can also try the latest kernel - 3.0.x and see if the problem
> > appears there as well - which is much easier for us to fix and has
> > some other important fixes that won't be back-ported to 2.6.32.
> 
> Since I'm using blktap2 I'm concerned about upgrading to 3.0.x.  I
> have read bad feedback about blktap-dkms.  Are my concerns unfounded?

No idea. I have never used blktap*.

>  Are there any alternative to blktap2 (excluding LVM)?

qdisk can do some of it. It is not as fast, but it can deal with
'tap:aio' and such. Or even a normal disk image 'file://'
> Thanks
> 
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