Re: [Xen-users] Serial Passthrough broken in Debian Wheezy?

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-06-03 at 17:25 +0200, Jonas Meurer wrote:
> Hello,
> 
> did anybody else discover issue with serial passthrough on Linux 3.2.0 
> from Debbian Wheezy?

I haven't, but Squeeze was based on the out of tree xen.git kernel while
Wheezy uses the mainline pvops support, so this is probably an issue
with the mainline kernel. I can't quite imagine what it would be though.

Are you able to try an newer upstream kernel in your domU? Either a
newer version from Debian Sid or wheezy-backports or a self compiled
one.

Ian.

> 
> Kind redgards,
>   jonas
> 
> 
> Am 2013-05-14 14:56, schrieb Jonas Meurer:
> > Hey again,
> > 
> > Am 13.05.2013 17:58, schrieb Jonas Meurer:
> >> I just discovered a strange bug with serial passthrough in xen 4.1 on
> >> Debian Wheezy. The Dom0 has a GSM modem connected to serial port. The
> >> serial port is passed through to a DomU with options 'irq = [ 4 ]' and
> >> 'ioports = [ '3f8-3ff ]'.
> > 
> > While searching the list archives I found out, that latest Xen 4.1 has
> > several issues with passthrough. But so far it seems to me like nobody
> > else described my exact issue before. Apparently, the other passthrough
> > issues have been introduced by a hypervisor update. My problem appeared
> > after a kernel upgrade. And for me, DomU creation still works. As
> > described, the passed through serial even exists in DomU. Only it
> > doesn't behave as expected.
> > 
> > Just wanted to share those additional observations.
> > 
> > Kind regards,
> >  jonas
> > 
> >> 
> >> This worked as expected on Debian Squeeze with Xen 4.0 and Linux 
> >> kernel
> >> 2.6.32 (both for Dom0 and DomU). On Debian Wheezy with Xen 4.1 and
> >> Linux kernel 3.2.0 the passthrough seems to work as well (/dev/ttyS0
> >> appears in dmesg of DomU), but something is wrong. The GSM modem
> >> doesn't behave as expected. The smstools daemon errors out with 
> >> 'Cannot
> >> open serial port /dev/ttyS0, error: Function not implemented'.
> >> 
> >> It took me hours to find the difference, but it seems like the guest
> >> (domU) kernel is the problem. The setup keeps working when Dom0 is
> >> upgraded to Debian Wheezy with Xen 4.1 and linux kernel 3.2.0. It even
> >> keeps working if the DomU userland is upgraded to Debian Wheezy. Only
> >> if I upgrade the DomU linux kernel to 3.2.0 from Wheezy as well,
> >> smstools stops working.
> >> 
> >> I don't expect this to be a smstools bug. More likely, something
> >> regarding serial pass through functions of xen is broken in 3.2.0
> >> kernel from Debian Wheezy.
> >> 
> >> Did anybody else discover similar issues yet?
> >> 
> >> Kind regards,
> >>  jonas
> >> 
> >> PS: I'm not subscribed to pkg-xen-devel@xxxxxxxxxxxxxxxxxxxxxxx, 
> >> please
> >> cc me on that list.
> >> 
> >> _______________________________________________
> >> Xen-users mailing list
> >> Xen-users@xxxxxxxxxxxxx
> >> http://lists.xen.org/xen-users
> > 
> > 
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> > http://lists.xen.org/xen-users
> 
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