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Re: [Xen-devel] [PATCH] - make qemu serial summagraphics settings a bitm

To: "Dugger, Donald D" <donald.d.dugger@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] - make qemu serial summagraphics settings a bitmore fluid
From: Ben Thomas <bthomas@xxxxxxxxxxxxxxx>
Date: Thu, 18 May 2006 17:30:26 -0400
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Hi Don,

I have this code running in another tree, so let me try to go
through these.  It's quite possible that qemu has outsmarted
me in this configuration.

Dugger, Donald D wrote:

I like the idea but I don't understand how this patch can work:

1)  You never put a name into `serial_devices[]' for the summa port.
The loop in `main' that initializes the serial devices only calls
`qemu_chr_open' if there's a string name in `serial_devices'.  How did
you get this to work?

I use -serial in the qemu command line.  For instance, I generally
use something like -serial pty -serial pty -serial null -serial pty,
which is asking for COM1, COM2 and COM4 assignments to a pty.  The model
is that you ask for a serial line, and also optionally indicate that you
want it to be summagraphics.

For instance, here's a command line that I just generated/used.
It requests multiple serial lines. none of which are summagraphic.

/bin/qemu-dm -d 7 -m 256 -monitor pty -serial pty -serial pty -serial pty
  -serial pty -vnc -vncconnect -k en-us -timeoffset -1800
  -vcpus 1 -macaddr 00:0f:4b:11:01:89 -bridge nexbr1 -hda /dev/dm-4
  -domain-name "Fedora Core 4 - 32 Bit"

2)  Minor point, I don't see the need for the `serial_summa' array, a
simple integer that is initialized to -1 would accomplish the same
thing.  (I have this thing about wasting memory :-)

I use the array so that I know which of the COMn ports are actually
using the Summagraphic protocols.  A bit array would work as well,
I suppose.

I chose to allow any/all/none of the ports to be running the protocol
and not just a fixed instance or only one.

3)  Personally, I hate counting serial ports from 1, everybody knows
that computers count from 0.  I'd refer to it as which `ttyS' port to
use, starting from 0, but I'm willing to live with the COM terminology.

Me, too.  I decided to follow the COM1/COM2/COM3/COM4 nomenclature as
this felt more like the PC hardware choice rather than an OS specific
choice.  I'd guess that Windows people won't be using ttyS, for instance.

How do you think we should proceed with this ?  My goal is quite
simple: allow some set (including none) of the serial lines to be
created and use the Summagraphics protocol (or not).

Does this make sense, or have I totally misunderstood something ?


Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
Ph: (303)440-1368

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ben Thomas
Sent: Thursday, May 18, 2006 12:50 PM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH] - make qemu serial summagraphics settings a bitmore fluid

Changeset 9967 made the qemu serial line Summagraphics support a little
more flexible with respect to the COM line chosen.  This patch
furthers that effort by removing the COM2 restriction.  This patch
allows a "-summa n" command line option to qemu to specify which, if
any, COM port should be using the Summagraphics protocols.

Signed-off-by: Ben Thomas (ben@xxxxxxxxxxxxxxx)

Ben Thomas Virtual Iron Software
bthomas@xxxxxxxxxxxxxxx                            Tower 1, Floor 2
978-849-1214 900 Chelmsford Street
                                                  Lowell, MA 01851

Ben Thomas                                         Virtual Iron Software
bthomas@xxxxxxxxxxxxxxx                            Tower 1, Floor 2
978-849-1214                                       900 Chelmsford Street
                                                   Lowell, MA 01851

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