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

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

[Ian Campbell]

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?

> However, the xl toolstack in 4.4 won't accept a list in the serial definition. If I change it to:
> 
> serial = "tcp::4464,server,nowait"
> serial = "file:/home/ed/logs/Tgt64bcom2.log"
> 
> I end up with a single serial port connected to the file.

Right, the second one has overwritten the first.

> How can I get two serial ports, with the first connected to a socket and the second connected to a file?

Until someone implements support for lists of serial devices as a
workaround you can pass arbitrary arguments to the qemu device model
using
        device_model_args=["--a thing", "--b another"]

It looks like the xm serial translated pretty directly into arguments to
-serial.

Ian.

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

[White, Edmund H]

> 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.

> > However, the xl toolstack in 4.4 won't accept a list in the serial definition. If I
> change it to:
> >
> > serial = "tcp::4464,server,nowait"
> > serial = "file:/home/ed/logs/Tgt64bcom2.log"
> >
> > I end up with a single serial port connected to the file.
> 
> Right, the second one has overwritten the first.
> 
> > How can I get two serial ports, with the first connected to a socket and the
> second connected to a file?
> 
> Until someone implements support for lists of serial devices as a workaround
> you can pass arbitrary arguments to the qemu device model using
>         device_model_args=["--a thing", "--b another"]
> 
> It looks like the xm serial translated pretty directly into arguments to -serial.
> 

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" ]

> Ian.
> 

Ed

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

[Ian Campbell]

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.

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

[White, Edmund H]

> 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

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

[Ian Campbell]

On Mon, 2014-07-28 at 16:41 +0000, White, Edmund H wrote:
> > 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.

Super, thanks!

> 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?

We need to support the old syntax for compat with old users, so [] needs
to be optional please.

> > > 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.

Oops, sorry. Do you have any suggestions for a change which would have
made the docs at least not so confusing?

Ian.