Re: [Xen-devel] [Xen-users] Multiple serial ports in Windows HVM

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-07-25 at 17:40 +0000, White, Edmund H wrote:
> > Subject: Re: [Xen-users] Multiple serial ports in Windows HVM
> > 
> > On Thu, 2014-07-24 at 20:08 +0000, White, Edmund H wrote:
> > > I have just moved from Xen 4.3 to 4.4. With 4.3 I used the xm toolstack, 
> > > and
> > I could define multiple serial ports in the config for my Windows domU like
> > so:
> > >
> > > serial = [ "tcp::4464,server,nowait",
> > > "file:/home/ed/logs/Tgt64bcom2.log" ]
> > 
> > I had no idea xm would accept a list here. We should probably look at
> > extending libxl/xl to support that. Is that something you think you could 
> > take
> > a look at?
> > 
> 
> I have literally no idea where to start, but if you give me some pointers 
> I'll take a look.

You would need to add a new field to libxl_domain_build_info.u.hvm in
tools/libxl/libxl_types.idl e.g. serial_list and add a LIBXL_HAVE
#define to libxl.h to signal the presence of this new field.

Then plumb it into tools/libxl/libxl_dm
libxl__build_device_model_args_*.

Lastly update xl_cmdimpl.c:parse_config_data to spot the use of a list
instead of a simple string and populate the new field (+ docs updates
etc).

George Dunlap did something very similar for the usb option in these two
commits:

c3a214819270 xl: Accept a list for usbdevice in config file
ac16730d0339 libxl: Allow multiple USB devices on HVM domain creation

I think you can pretty much just file off the usb and write serial in
its place ;-)

See http://wiki.xen.org/wiki/Submitting_Xen_Patches for more general
advice on the patch workflow etc.

> I had tried that without success before posting to the list. I tried again 
> today and
> now have it working. The successful recipe is to define the first serial port 
> with:
> 
> serial = "tcp::4464,server,nowait"
> 
> and the second with
> 
> device_model_args = [ "-serial", "file:/home/ed/logs/Tgt64bcom2.log" ]

Interesting. I'd have expected:
        device_model_args = [ "-serial", "tcp::4464,server,nowait",
                              "-serial", "file:/home/ed/logs/Tgt64bcom2.log" ]
by itself to also work equally well.

Ian.


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