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Groups > linux.kernel > #1539173
| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC PATCH 0/3] staging: remove fbdev drivers |
| Date | 2016-12-09 09:10 +0100 |
| Message-ID | <sMopH-PU-3@gated-at.bofh.it> (permalink) |
| References | <sGAMV-2jc-3@gated-at.bofh.it> <sLVnH-7LF-7@gated-at.bofh.it> <sM3XX-4Va-3@gated-at.bofh.it> <sMfw5-3sC-9@gated-at.bofh.it> <sMgVb-4sj-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Hi Dave,
On Fri, Dec 9, 2016 at 1:08 AM, Dave Airlie <airlied@gmail.com> wrote:
> On 9 December 2016 at 07:28, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
>> On Thu, 2016-12-08 at 11:10 +0100, Daniel Vetter wrote:
>>> > With drmfb you basically have to shadow everything into memory & copy
>>> > over everything, and locks you out of simple 2D accel. For a simple text
>>> > console the result is orders of magnitude slower and memory hungry than
>>> > a simple fbdev.
>>>
>>> Not true, we have full fbdev emulation, and drivers can implement the 2d
>>> accel in there. And a bunch of them do. It's just that most teams decided
>>> that this is pointless waste of their time.j
>>
>> Ok so my knowledge might be outdated here. I was complaining to Dave about
>> how cirrusdrmfb didn't even use blits for fbcon scrolling and always double
>> buffered everything, and Dave made the point that you basically had to do
>> that for security reasons that I mostly forgot the details of.
>>
>> It looks like bochsdrmfb and astdrmfb are the same. If things have changed,
>> then cool. Can you point me to a drmfb driver that is a good (and not too
>> complex) example with simple 2d accel ? I'm thinking mostly of color
>> expansion, bitblt and solid fill for fbcon, the way I used to do it in
>> radeonfb for example.
>
> What are people using fbcon for that needs acceleration, this is where I get
> a bit lost.
>
> It's a console, if you aren't sshing into the machine.
>
> It's main purpose should just be for gathering oopses and you've a lot better
> chance of getting an oops if you don't have some sketchy gpu accel in the way.
Unless you're using the console as a text console, and don't run e.g. X on top.
> The acceleration that most of the 2D things provide isn't ever that
> great, and shadowing is a lot more effective if done properly. It's a feature
> that kernel ppl obsess over but I don't get a lot of real world feedback,
> (booting 9000 scsi nodes with debug on takes a long time was possibly
> something I heard once, and I think we resolved).
It all depends on the complex balance between GPU performance, CPU performance,
CPU-to-frame buffer bandwidth, and amount of available system RAM.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 02:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-12-08 09:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 22:30 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 22:50 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 09:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-08 11:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 13:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-08 15:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 15:30 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Thomas Petazzoni <thomas.petazzoni@free-electrons.com> - 2016-12-08 15:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 15:50 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-08 16:30 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 22:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 23:00 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 09:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 09:50 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-09 12:50 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 14:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-09 22:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-09 12:50 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-09 13:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Lucas Stach <l.stach@pengutronix.de> - 2016-12-09 14:20 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 14:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers David Herrmann <dh.herrmann@gmail.com> - 2016-12-09 15:00 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 15:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-09 21:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-09 09:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Jani Nikula <jani.nikula@linux.intel.com> - 2016-12-08 16:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Daniel Vetter <daniel@ffwll.ch> - 2016-12-08 15:30 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-08 23:40 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Dave Airlie <airlied@gmail.com> - 2016-12-09 01:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-09 09:10 +0100
Re: [RFC PATCH 0/3] staging: remove fbdev drivers Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-12-09 12:50 +0100
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