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

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.



Trolle Selander wrote:
This is a HVM DomU, so you need to use an emulated serial port backed by
physical port. There is no support for assigning physical serial port
resources to "give" the serial port directly to the HVM DomU.
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
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 -
working on improving this particular code right now, so if you run into
strangeness, I'll probably know what's going on and be able to help. :)

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