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

[Sadique Puthen <sputhenp@xxxxxxxxxx>]

What is the output of "dmesg | grep ttyS" in dom0?

--Sadique


Hans Rakers wrote:
> Hello xen-users,
>
> Last days i've been pulling my hair on getting ttyS0 (COM1) to work in 
> a HVM DomU. I want to use it for an external faxmodem for use with 
> Hylafax. I've Googled myself crazy and have seen just about every page 
> on this subject :)
> My system is CentOS 5.1 with xen-3.0.3-41.el5. I've added xencons=off 
> to grub.conf of DomU and i've added the following to 
> /etc/modprobe.d/blacklist:
> blacklist 8250
> blacklist 8250_pnp
> blacklist serial_core
>
> I can confirm that Dom0 does not claim the serial ports (no mention of 
> it during boot, no modules loaded, xencons off)
> My DomU also runs CentOS 5.1. I've added the following to its vm config:
>
> irq = [3, 4]
> ioports = ["3f8-3ff", "2f8-2ff"]
>
> Syslog of the DomU mentions the loading of the 8250 module, but no 
> resulting ports:
> Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled
>
> /proc/ioports of the DomU also doesn't mention the mapped ioports:
>
> [...snip snip...]
> 01f0-01f7 : ide0
> 03c0-03df : vga+
> 03f2-03f5 : floppy
> 03f6-03f6 : ide0
> 03f7-03f7 : floppy DIR
> 0cf8-0cff : PCI conf1
> [...snip snip...]
>
> Is this at all possible, or am i overlooking something stupid? Do 
> 'ioports' and 'irq' work with fully virtualized VM's? I've read 
> something earlier on this list at 
> http://lists.xensource.com/archives/html/xen-users/2007-08/msg00838.html 
> which states that it is impossible for HVMs to have direct access to 
> hardware, which is why i ask, before spending another day on this :)
> Thanks in advance,
>
> Hans Rakers
>
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