[PATCH] fbdev: Remove udlfb driver

[Thomas Zimmermann]

Am 02.12.20 um 08:55 schrieb Thomas Zimmermann:
> Hi
> 
> Am 01.12.20 um 12:20 schrieb Mikulas Patocka:
>>
>>
>> On Tue, 1 Dec 2020, Thomas Zimmermann wrote:
>>
>>> Hi
>>>
>>> Am 30.11.20 um 19:39 schrieb Mikulas Patocka:
>>>>
>>>>
>>>> On Mon, 30 Nov 2020, Daniel Vetter wrote:
>>>>
>>>>> On Mon, Nov 30, 2020 at 09:31:15AM -0500, Mikulas Patocka wrote:
>>>>>>
>>>>>> The framebuffer driver supports programs running full-screen 
>>>>>> directly on
>>>>>> the framebuffer console, such as web browser "links -g", image viewer
>>>>>> "fbi", postscript+pdf viewer "fbgs", ZX Spectrum emulator "fuse-sdl",
>>>>>> movie player "mplayer -vo fbdev". The DRM driver doesn't run them.
>>>>>
>>>>> Hm this should in general work on drm drivers. Without that it's 
>>>>> clear the
>>>>> switch-over isn't really ready yet.
>>>>
>>>> I fixed it with this patch two years ago:
>>>> https://lists.freedesktop.org/archives/dri-devel/2018-June/179023.html
>>>>
>>>> But the patch never went through and the fb_defio feature was 
>>>> removed in
>>>> the kernel 5.6 (commit d0c4fc5a4814e431c15272935c8dc973c18073aa).
>>>>
>>>>
>>>> Without fb_defio, the only other possibility how to update the 
>>>> screen is
>>>> the ioctl DRM_IOCTL_MODE_DIRTYFB. But this ioctl requires master 
>>>> mode, so
>>>> user programs like "links -g" can't issue it.
>>>
>>> That's confusing. DIRTYFB is only for DRM.
>>
>> Yes, you're right.
>>
>>> And why can links not run as DRM master mode? If it renders to the 
>>> terminal,
>>> it should act like a composer. In that case it almost certainly wants 
>>> master
>>> status.
>>>
>>> Best regards
>>> Thomas
>>
>> How can a userspace program acquire master mode without being suid?
> 
> For my understanding, there's no easy solution to that. :/
> 
> I guess we (DRM devs) have to treat fbdev as the solution for use cases 
> such as ours.

s/ours/yours

> 
> For the unplug issue, I'll try to reproduce and fix it.
> 
> For the performance problems, we might be able to squeeze a few more 
> cycles out of it.
> 
> Best regards
> Thomas
> 
>>
>> Is there some "Hello World!" program that shows how to use DRM? I'm 
>> not an
>> expert in DRM, but if there were some tutorial+documentation, I could
>> consider porting "links" to it.
>>
>> Mikulas
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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