[xen-tools-dev] xen-create-image: allow xvc0 in --serial_device option.

[Jorge Armando Medina]

On 09/20/2010 12:23 PM, Dmitry Nedospasov wrote:
> Hello Jorge,

Hi everyone,

>
> On Mon, Sep 20, 2010 at 11:43:36AM -0500, Jorge Armando Medina wrote:
>> Hi there,
>> 1. hvc0 is the default hardcoded in /usr/bin/xen-create-image, I think
>> it is better to default it in xen-tools.conf.
>
> The reason for this is actually that hvc0 is the recommended setting for
> xen, and it should be the default for all "newer" domUs. Xen
> unfortunately used several "default" serial devices before ariving at
> today's hvc0.

You are right about hvc0 and newer versions, I still have a few servers 
with with ubuntu 8.04 (LTS), both dom0 and domu, with xen 3.2 from 
packages or xen 3.4 from source and linux-image-2.6.24-28-xen, and I 
would like to use a recent version of xen-tools that allows me to set 
default parameters like this:

dist = hardy
arch = amd64
serial_device = xvc0

and be able to use xen-create-image --dist=lenny --serial_device=hvc0 
--pygrub ...

Or the oposite for my customers with lenny as dom0 and domU:


dist = lenny
arch = amd64
serial_device = hvc0

and be able to use xen-create-image --dist=hardy --serial_device=xvc0 
--pygrub ...

My point is that, most people I asked is that we prefer to set the 
serial_device default parameter in the the global configuration file (as 
stated in xen-create-image(8))  /etc/xen-tools/xen-tools.conf
insted that modifying /usr/bin/xen-create-image and changing the line:

     $CONFIG{ 'serial_device' } = 'hvc0';


I think that the change involves uncommenting the line:

# serial_device = hvc0 #default

in xen-tools.conf

and change xen-create-image to:

     $CONFIG{ 'serial_device' } = '';

And also the help:

    --serial_device=serialname
                 Install a getty on the specified serial device instead
                 of the default device.

To:

    --serial_device=serialname
                 Install a getty on the specified serial device instead
                 of the default device, the default value hvc0.

We already have instructions about defining/changing default values in 
the global configuration file xen-tools.



>
>> I change it to
>>
>>          serialDev =>  {
>>              check   =>  qr/^(?:\/dev\/)?(?:tty|[xh]vc)[0-9]+$/,
>>              message =>  "must be a serial device (tty*, hvc* or xvc*).\n",
>>          },
>
> Looks simple enough.
>
>> Another note, probably would be good to have this same validation for
>> xen-tools.conf, because it accepts what ever value you use.
>
> Will have to investigate, but this is an interesting point that i forgot
> to test :P AFAIK the options will still get parsed and checked though.
>
>> Best regards and I hope you can include this simple fix because xvc0 is
>> used in a few hooks.
>
> Okay agreed, though I'm not entirely sure that we shouldn't just use
> hvc0 and remove xvc0 from the scripts. If you have legacy vms that you
> are importing, it is still possible to set them via .cfg file. Again,
> new machines *SHOULD NOT* use anything other than hvc0 acording to the
> xen documentation.

Yes, but editing the .cfg file will remove the flexibility described 
above for new and legacy versions.

Another point, not me but I know people that use xen-tools in centos 5 
with xen 3.1 and 2.6.18 kernels, they will benefit from this change :).

Best regards.
>
> Thanks,
>
> D.


-- 
Compugraf