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

["White, Edmund H" <edmund.h.white@xxxxxxxxx>]

> 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.
> 

OK. I will look into it.

One question: should the end result be that you can use a single item OR a list,
or a list only? In other words, should [] be optional or mandatory?

> > 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.
> 

It may have done, but I was concerned that if I didn't define the first serial 
port through 'serial =' there
would be some default that I didn't want.

My original attempts were failing because I was placing "-serial value" in a 
single string (as both the docs and
your original reply imply), and that results in something that looks correct 
but which qemu can't parse properly.

> Ian.

Ed

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