Re: [Xen-devel] question about PXE

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

> Failed to obtain physical IRQ 4

Physical IRQ 4 is normally used by serial UARTs.

Have you enabled support for e.g. the 16550 uart in your dom0
kernel config, but have also told xen to use com1 ?  It's
generally best to let xen have com1, then the virtual xencons
driver will enable Linux to share the serial line with xen. This
what happens with the default.
 
> 2. I don't know if this is related, but after I'm logged in, then "xend
> start" cuts off all network access.  I assume this has something to do
> with the bridging code, but I can't figure out what.  A look at
> xen.xend.* didn't help me much.  The brctl tools seem to be working
> normally.  I feel like I'm missing something obvious..

Odd. Add 'bash -x' at the top of the /etc/xen/scripts/network
and then you should be able to see what the script is doing.

It creates a bridge and then attempts to transfer the original
network setup over to the bridge. Positing the output of
"ip link show" and "ip route show" before and after should help
figure out what's going wrong.
 
> 3. This seems related to the first problem, I get this error when trying
> to add the tun module:
> 
> # modprobe tun
> /lib/modules/2.4.27-xen0/kernel/drivers/net/tun.o: init_module: Input/output 
> error
> Hint: insmod errors can be caused by incorrect module parameters, including 
> invalid IO or IRQ parameters
> /lib/modules/2.4.27-xen0/kernel/drivers/net/tun.o: insmod 
> /lib/modules/2.4.27-xen0/kernel/drivers/net/tun.o failed
> /lib/modules/2.4.27-xen0/kernel/drivers/net/tun.o: insmod tun failed

Odd. Are you sure you installed the modules that were built for
this kernel version?

Out of interest, what do you want to use tun for? Hosting other
UML instances from withing xen guest instances? I guess this
should work, though I've never tried it.

Ian