Re: [Qemu-devel] [6352] Fix character devices after DisplayState refactoring

[Anthony Liguori <anthony@codemonkey.ws>]

Stefano Stabellini wrote:
> Anthony Liguori wrote:
>
>   
>> Revision: 6352
>>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6352
>> Author:   aliguori
>> Date:     2009-01-16 20:23:27 +0000 (Fri, 16 Jan 2009)
>>
>> Log Message:
>> -----------
>> Fix character devices after DisplayState refactoring
>>
>> The DisplayState refactoring changed the machine init function to create a
>> DisplayState for each VGA device instead of being passed an existing
>> DisplayState.  This change is critical to enable multiple graphics device
>> support.
>>
>> Unfortunately, the serial/parallel/console code is structured today to run
>> before machine init to fill out the CharDriverState table which the machine
>> init function uses to determine whether to create the required devices.
>>
>> Since a 'vc' is a type of CharDriverState, the CharDriverState code requires
>> that a DisplayState exist before it runs creating a circular dependency.
>>
>> To fix this, this splits the creation of the initial CharDriverState from
>> the initialization of the text console.  We can then in a second step associate
>> a DisplayState with all TextConsoles.  This allows us to create the
>> CharDriverState's first, machine init, then associate the TextConsoles with
>> a DisplayState.
>>
>> This code screams for more cleanup.
>>
>>     
>
> I am sorry for this.
>   

No worries.  What I meant about more cleanup was that this patch series 
demonstrated a fundamental flaw in the CharDriverState abstraction.  
That is, we really ought to separate the creation of a CharDriverState 
front-end from the creation of the back-end.

We should then attach a front-end to a back-end.  This would make it 
easy to dynamically change the back-end of any given CharDriverState 
which is something I've liked to see for a while now.

Regards,

Anthony Liguori

> While I was testing the patch series I was expecting many rendering
> issues or console switching issues: once I saw that both the serial and
> parallel port consoles were present I didn't check they were actually
> working.
>
>
>
>