Standard VGA console with DRI/DRM under X?

Standard VGA console with DRI/DRM under X?

[Michael Shell]

  Greetings,

Well, I want to be able to have my cake and eat it too. I want to be able to
have the standard VGA/"hardware" classic console (not the framebuffer) but
I still want the /dev/dri/cardX devices so that I can use DRI under Xorg.

Is this possible and if not, why not?


(I do hope I'm not bring up an issue with an obvious fix, but my searching
 has not yielded an answer yet. For the record, I'm running modern kernel
 (3.16.3) with much older x86 hardware [r100 Radeon video card].)


If I boot with the kernel nomodeset option I can get the classic
VGA/"hardware" console, but then I lose support for DRI/DRM:

Oct 27 15:11:09 X kernel: [drm] Initialized drm 1.1.0 20060810
Oct 27 15:11:09 X kernel: [drm] VGACON disable radeon kernel modesetting.
Oct 27 15:11:09 X kernel: [drm:radeon_init] *ERROR* No UMS support in radeon module

and glxgears et al. turns slow. In more modern Xorg releases, DRI is
required for all hardware acceleration, so having /dev/dri/cardX is very
important:

http://askubuntu.com/questions/463142/why-x-is-relying-on-software-instead-of-hardware-with-nomodeset-kernel-paramet


One reason I do not wish to use the framebuffer console is because of the
small font. 160 columns makes it difficult to tell which [OK] belongs with
which service. The selection of console fonts should always include a
set that gives us an 80 column screen and the docs should point this out.

And I dislike any blanking or video mode changes during boot.

Can't the kernel just declare that it is capable of setting the video mode,
provide the /dev/dri/cardX devices and leave the console alone, but still
allow Xorg to call for a new mode and use /dev/dri/cardX if/when it sees fit?

In an ideal world, there would be some kernel option such as fbcon=no.

In the kernel Documentation fbcon.txt it mentions "fbcon=map:1 tells fbcon not
to take over the console." But, IIRC, from my tests I wasn't able to use this
to get a VGA/"hardware" console and still be able to have /dev/dri/cardX devices.



    Cheers and thank you,

    Mike Shell

Re: Standard VGA console with DRI/DRM under X?

[Bjorn Helgaas]

[+cc David, Alex, Christian, dri-devel]

On Tue, Oct 28, 2014 at 12:32 AM, Michael Shell <list1@michaelshell.org> wrote:
>
>
>   Greetings,
>
> Well, I want to be able to have my cake and eat it too. I want to be able to
> have the standard VGA/"hardware" classic console (not the framebuffer) but
> I still want the /dev/dri/cardX devices so that I can use DRI under Xorg.
>
> Is this possible and if not, why not?
>
>
> (I do hope I'm not bring up an issue with an obvious fix, but my searching
>  has not yielded an answer yet. For the record, I'm running modern kernel
>  (3.16.3) with much older x86 hardware [r100 Radeon video card].)
>
>
> If I boot with the kernel nomodeset option I can get the classic
> VGA/"hardware" console, but then I lose support for DRI/DRM:
>
> Oct 27 15:11:09 X kernel: [drm] Initialized drm 1.1.0 20060810
> Oct 27 15:11:09 X kernel: [drm] VGACON disable radeon kernel modesetting.
> Oct 27 15:11:09 X kernel: [drm:radeon_init] *ERROR* No UMS support in radeon module
>
> and glxgears et al. turns slow. In more modern Xorg releases, DRI is
> required for all hardware acceleration, so having /dev/dri/cardX is very
> important:
>
> http://askubuntu.com/questions/463142/why-x-is-relying-on-software-instead-of-hardware-with-nomodeset-kernel-paramet
>
>
> One reason I do not wish to use the framebuffer console is because of the
> small font. 160 columns makes it difficult to tell which [OK] belongs with
> which service. The selection of console fonts should always include a
> set that gives us an 80 column screen and the docs should point this out.
>
> And I dislike any blanking or video mode changes during boot.
>
> Can't the kernel just declare that it is capable of setting the video mode,
> provide the /dev/dri/cardX devices and leave the console alone, but still
> allow Xorg to call for a new mode and use /dev/dri/cardX if/when it sees fit?
>
> In an ideal world, there would be some kernel option such as fbcon=no.
>
> In the kernel Documentation fbcon.txt it mentions "fbcon=map:1 tells fbcon not
> to take over the console." But, IIRC, from my tests I wasn't able to use this
> to get a VGA/"hardware" console and still be able to have /dev/dri/cardX devices.
>
>
>
>     Cheers and thank you,
>
>     Mike Shell
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: Standard VGA console with DRI/DRM under X?

[Christian König]

> Is this possible and if not, why not?
Long story short on modern hardware the VGA console is just an emulation 
working on top of the real hardware. When the driver wants to talk to 
the real hardware it must simply disable the VGA emulation first.

But to me all points why you don't like the fbcon are just a matter of 
configuring it correctly, so you might want to look into that direction 
as well.

Regards,
Christian.

Am 28.10.2014 um 16:48 schrieb Bjorn Helgaas:
> [+cc David, Alex, Christian, dri-devel]
>
> On Tue, Oct 28, 2014 at 12:32 AM, Michael Shell <list1@michaelshell.org> wrote:
>>
>>    Greetings,
>>
>> Well, I want to be able to have my cake and eat it too. I want to be able to
>> have the standard VGA/"hardware" classic console (not the framebuffer) but
>> I still want the /dev/dri/cardX devices so that I can use DRI under Xorg.
>>
>> Is this possible and if not, why not?
>>
>>
>> (I do hope I'm not bring up an issue with an obvious fix, but my searching
>>   has not yielded an answer yet. For the record, I'm running modern kernel
>>   (3.16.3) with much older x86 hardware [r100 Radeon video card].)
>>
>>
>> If I boot with the kernel nomodeset option I can get the classic
>> VGA/"hardware" console, but then I lose support for DRI/DRM:
>>
>> Oct 27 15:11:09 X kernel: [drm] Initialized drm 1.1.0 20060810
>> Oct 27 15:11:09 X kernel: [drm] VGACON disable radeon kernel modesetting.
>> Oct 27 15:11:09 X kernel: [drm:radeon_init] *ERROR* No UMS support in radeon module
>>
>> and glxgears et al. turns slow. In more modern Xorg releases, DRI is
>> required for all hardware acceleration, so having /dev/dri/cardX is very
>> important:
>>
>> http://askubuntu.com/questions/463142/why-x-is-relying-on-software-instead-of-hardware-with-nomodeset-kernel-paramet
>>
>>
>> One reason I do not wish to use the framebuffer console is because of the
>> small font. 160 columns makes it difficult to tell which [OK] belongs with
>> which service. The selection of console fonts should always include a
>> set that gives us an 80 column screen and the docs should point this out.
>>
>> And I dislike any blanking or video mode changes during boot.
>>
>> Can't the kernel just declare that it is capable of setting the video mode,
>> provide the /dev/dri/cardX devices and leave the console alone, but still
>> allow Xorg to call for a new mode and use /dev/dri/cardX if/when it sees fit?
>>
>> In an ideal world, there would be some kernel option such as fbcon=no.
>>
>> In the kernel Documentation fbcon.txt it mentions "fbcon=map:1 tells fbcon not
>> to take over the console." But, IIRC, from my tests I wasn't able to use this
>> to get a VGA/"hardware" console and still be able to have /dev/dri/cardX devices.
>>
>>
>>
>>      Cheers and thank you,
>>
>>      Mike Shell
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel

RE: Standard VGA console with DRI/DRM under X?

[Deucher, Alexander]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 4069 bytes --]

> -----Original Message-----
> From: Bjorn Helgaas [mailto:bhelgaas@google.com]
> Sent: Tuesday, October 28, 2014 11:48 AM
> To: Michael Shell
> Cc: linux-kernel@vger.kernel.org; David Airlie; DRI mailing list; Deucher,
> Alexander; Koenig, Christian
> Subject: Re: Standard VGA console with DRI/DRM under X?
> 
> [+cc David, Alex, Christian, dri-devel]
> 
> On Tue, Oct 28, 2014 at 12:32 AM, Michael Shell <list1@michaelshell.org>
> wrote:
> >
> >
> >   Greetings,
> >
> > Well, I want to be able to have my cake and eat it too. I want to be able to
> > have the standard VGA/"hardware" classic console (not the framebuffer)
> but
> > I still want the /dev/dri/cardX devices so that I can use DRI under Xorg.
> >
> > Is this possible and if not, why not?
> >
> >

It's not currently possible.  When the driver loads it needs to reprogram the GPU memory controller which requires disabling (or at least blanking the displays).  Additionally there is currently no code in the driver to setup the vga text mode emulation.  Moreover, there is no legacy vga text mode on UEFI systems when the GPU has a GOP driver.

> > (I do hope I'm not bring up an issue with an obvious fix, but my searching
> >  has not yielded an answer yet. For the record, I'm running modern kernel
> >  (3.16.3) with much older x86 hardware [r100 Radeon video card].)
> >
> >
> > If I boot with the kernel nomodeset option I can get the classic
> > VGA/"hardware" console, but then I lose support for DRI/DRM:
> >
> > Oct 27 15:11:09 X kernel: [drm] Initialized drm 1.1.0 20060810
> > Oct 27 15:11:09 X kernel: [drm] VGACON disable radeon kernel
> modesetting.
> > Oct 27 15:11:09 X kernel: [drm:radeon_init] *ERROR* No UMS support in
> radeon module
> >
> > and glxgears et al. turns slow. In more modern Xorg releases, DRI is
> > required for all hardware acceleration, so having /dev/dri/cardX is very
> > important:
> >
> > http://askubuntu.com/questions/463142/why-x-is-relying-on-software-
> instead-of-hardware-with-nomodeset-kernel-paramet
> >

UMS is deprecated in the kernel and support for UMS has been dropped from the X ddx and the mesa drivers. Moreover, UMS had a lot of limitations that make it much less useful for modern desktops (no DRI2 support, no display hotplug support, etc.).

> >
> > One reason I do not wish to use the framebuffer console is because of the
> > small font. 160 columns makes it difficult to tell which [OK] belongs with
> > which service. The selection of console fonts should always include a
> > set that gives us an 80 column screen and the docs should point this out.
> >
> > And I dislike any blanking or video mode changes during boot.
> >
> > Can't the kernel just declare that it is capable of setting the video mode,
> > provide the /dev/dri/cardX devices and leave the console alone, but still
> > allow Xorg to call for a new mode and use /dev/dri/cardX if/when it sees
> fit?
> >
> > In an ideal world, there would be some kernel option such as fbcon=no.
> >
> > In the kernel Documentation fbcon.txt it mentions "fbcon=map:1 tells
> fbcon not
> > to take over the console." But, IIRC, from my tests I wasn't able to use this
> > to get a VGA/"hardware" console and still be able to have /dev/dri/cardX
> devices.
> >

The driver disables the legacy vga text mode hardware when it loads.  I think configuring a different mode or font for the fb console would probably get you what you want.  See the Forcing Modes section of this page (http://nouveau.freedesktop.org/wiki/KernelModeSetting/) for how to select a custom mode for your display with KMS

Alex

> >
> >
> >     Cheers and thank you,
> >
> >     Mike Shell
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: Standard VGA console with DRI/DRM under X?

[Pavel Machek]

On
> One reason I do not wish to use the framebuffer console is because of the
> small font. 160 columns makes it difficult to tell which [OK] belongs with
> which service. The selection of console fonts should always include a
> set that gives us an 80 column screen and the docs should point this
>out.

Take a look at kernel config, and select a bigger font.
									Pavel


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html