Re: [Xen-users] Serial port access in HVM (fully virtualized) DomU

[Sadique Puthen <sputhenp@xxxxxxxxxx>]

dbrunell wrote:
> I'm having a similar problem with opensuse 10.2 and Xen 3.0.3.  I cannot get
> Xen to release ttyS0 to Dom0, even with xencons=off or xencons=tty.  There
> is no ttyS0 in dmesg and I get an invalid port message if I try to run
> minicom on it.  However, if I reboot without the Xen kernel the port works
> fine (shows up in dmesg and works in minicom).
>
> Any ideas on how to troubleshoot this?
>   
Pass "console=xvc console=tty0 xencons=xvc" in the kernel line of the 
grub.conf in dom0. I have the below line
title Red Hat Enterprise Linux Server (2.6.18-53.1.4.el5xen)
       root (hd0,0)
       kernel /xen.gz-2.6.18-53.1.4.el5
       module /vmlinuz-2.6.18-53.1.4.el5xen ro 
root=/dev/VolGroup00/LogVol00 rhgb quiet console=xvc console=tty0 
xencons=xvc
       module /initrd-2.6.18-53.1.4.el5xen.img

Then check dmesg after this.

--Sadique
> Regards,
>
> David
>
>
>
> Trolle Selander wrote:
>   
> > This is a HVM DomU, so you need to use an emulated serial port backed by
> > the
> > physical port. There is no support for assigning physical serial port
> > resources to "give" the serial port directly to the HVM DomU.
> > Theoretically,
> > this should be fairly easily doable even on IOMMU-less systems, but as far
> > as I know. there's no code to do this yet for HVMs. Serial ports on a
> > separate PCI card should be possible to using the PCI passthrough feature
> > in
> > recent versions of xen.
> >
> > However, the emulated device may work fine for you, with much less hassle.
> > Just make sure that your serial ports _are_ available to Dom0 (that is,
> > remove the blacklist entries), and then add serial=/dev/ttyS0 to your HVM
> > domain config. There are some caveats with serial emulation currently -
> > I'm
> > working on improving this particular code right now, so if you run into
> > any
> > strangeness, I'll probably know what's going on and be able to help. :)
> >
> >
> >
> >     
>   

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