There were some changes made recently in core Xen involving the serial port. The latest Xen/ia64 from xeno-unstable.bk contains these changes and some additional changes to the ia64-specific files to accommodate the core changes.

The core changes are very particular about the format of the command line -- I'm not sure I fully understand yet what variations work and what variations don't work. If it doesn't work, there is no way to put out an error message (though the core Xen code trys to :-)

Here's what I think works: (This will find its way into a README file soon.)

1) If your machine supports EFI PCDP (I'm told many HP machines do), Xen/ia64 will attempt to read console information directly out of EFI HCDP. In some cases it can figure out the console, in others it can't. If it can, the command line for Xen should be the same as before, meaning no explicit console... the entire command line is passed to domain0.

So your elilo.conf file may have something like this:

image=xen label=xen initrd=xenlinux read-only append="console=ttyS0,115200 root=/dev/sda2"

2) If your machine doesn't support PCDP (or does but Xen can't figure it out), the Xen console must be provided in a very specific format. The Xen command line is now separated from domain0 in the elilo.conf file using a double-dash:

xenarg1 xenarg2 -- dom0arg1 dom0arg2 domarg3

The Xen console must be specifed as comX=baud,bits,addr,irq, for example:

com1=115200,8n1,0xff5e0000,9

This works on my machine. The following works on another machine with an SMP (management card):

com1=115200,8n1,0xf4050000,9

So your elilo.conf file may have something like this:

image=xen label=xen initrd=xenlinux read-only append="com1=115200,8n1,0xff5e0000,9 -- console=ttyS0,115200 root=/dev/sda2"

If you specify any com1= parameter in the Xen part, this overrides any attempt for Xen to try to use PCDP.

Note that the irq number will be necessary for keyboard input which doesn't currently work in Xen/ia64 so is a no-op right now.

3) If your box is PC-compliant (most Intel boxes I'm told), the default Xen core code may just work... I don't think any Xen command line needs to be specified.

This is all brand new so is subject to change.