Re: [PATCH] x86/platform: Protect XENPF_get_dom0_console if CONFIG_VIDEO not set

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.12.2022 11:38, Michal Orzel wrote:
> Hi Jan,
> 
> On 07/12/2022 11:34, Jan Beulich wrote:
>>
>>
>> On 07.12.2022 11:29, Michal Orzel wrote:
>>> A build failure [1] is observed if CONFIG_VGA (and thus CONFIG_VIDEO) is
>>> not set. This is because XENPF_get_dom0_console cmd of platform hypercall
>>> makes a call to fill_console_start_info, which is defined in video/vga.c
>>> and built only if CONFIG_VGA is set.
>>
>> Which means to use ...
>>
>>> --- a/xen/arch/x86/platform_hypercall.c
>>> +++ b/xen/arch/x86/platform_hypercall.c
>>> @@ -839,6 +839,7 @@ ret_t do_platform_op(
>>>      }
>>>      break;
>>>
>>> +#ifdef CONFIG_VIDEO
>>
>> ... CONFIG_VGA here, unless fill_console_start_info() was moved to a file
>> that's built dependent upon CONFIG_VIDEO.
> The one and only reason of using CONFIG_VIDEO and not CONFIG_VGA is that all 
> the
> calls in existing codebase to fill_console_start_info are protected by 
> CONFIG_VIDEO
> and not CONFIG_VGA. That is why I choose to stick to the current behavior.

"All" is interesting as a statement when there's just one. But yes, I
can see that the issue is broader - 2b8a95a2961b ("xen/x86: make VGA
support selectable") didn't really get the #ifdef-s right. I guess the
change then is okay as is:
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
and we'll need to touch all of that again (or move code around) if some
2nd way of selecting VIDEO appears.

Jan