[Libguestfs] virt-v2v should add kernel console= to Xen->KVM converted guest's grub.conf

[Matthew Booth]

On 01/06/2012 11:48 PM, Chuck Anderson wrote:
> On Thu, Jan 05, 2012 at 07:10:38PM -0500, Chuck Anderson wrote:
>> I'd like to propose that the converter add such kernel console=
>> arguments if it doesn't find any to replace.
>
> I figured out something that works.  This change will continue to
> update any existing console arguments that mention xvc0 or hvc0 and
> modify those references to ttyS0.  Additionally, this change will add
> a new console=ttyS0,115200 to any kernel lines that don't have any
> existing console argument.
>
> --- RedHat.pm.orig	2011-12-08 18:09:16.000000000 -0500
> +++ RedHat.pm	2012-01-06 18:38:33.224309303 -0500
> @@ -383,6 +383,15 @@
>           }
>       }
>
> +    # Add console to any kernel line that doesn't have one
> +    foreach my $augpath
> +        ($g->aug_match("/files$grub_conf/title[count(kernel/console) = 0]"))
> +    {
> +	my $console_augpath = "$augpath/kernel/console";
> +	my $console = "ttyS0,115200";
> +	$g->aug_set($console_augpath, $console);
> +    }
> +
>       eval {
>           $g->aug_save();
>       };
>
> Would you consider taking such a patch?

We discussed this on IRC on Friday. I don't think we can be quite this 
simple, because this would be a surprising change for a user 
intentionally using the graphical console on Xen HVM or VMWare. This is 
pretty common (in fact I believe most users do this).

We therefore need to special case a Xen PV guest with no kernel console 
line. This unfortunately won't be as straightforward as this patch 
because there are currently no hooks in V2V to direct particular 
features to be enabled during conversion. I agree that we should be 
doing something like this, though.

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

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