videowall

videowall

[Christian Stöveken]

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So I had this crazy idea to put together a cheap video
wall<https://lh6.googleusercontent.com/-GNJ97iKoU3Y/UumgZ62KESI/AAAAAAAAa8Y/t07wL1D7Tmk/w931-h698-no/IMG_20140125_210754.jpg>
in
my local hackerspace using
a lot of screens suffering from planned obsolescence or at least a poor
choice in their used caps
and cheap - used Nvidia NVS 440 cards.

During evaluation of Win 7/8 I noticed there was an 8 gpu OS limit that I
didn't know of before.
I also ran into that limt using the proprietary nvidia driver on Linux.

So now I'm trying to see how far nouveau is in regards to "multiple" gpu's
and
after 3 evenigs of fiddling with mostly xorg.conf I just got the first 4
gpu's / 8 displays working.

I'm stuck on the 3rd card / gpu 5+6 / monitors 9-12.

Without spending another few evenings I thought I might check in with you
guys first whether
you think it's possible driving a 6400x4096 video wall with nouveau
and 5 Nvidia NVS 440 cards (NV43) (10 gpus with dual head) - if not I might
be willing to donate
the cards for development if someone is interested.


Best Regards,
Christian

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Re: videowall

[Greg]

Hi there,

Unfortunately, I can not help you but I have similar problem (but 
significantly smaller, see:
http://lists.freedesktop.org/archives/nouveau/2014-January/015855.html )

On 01/30/14 02:18, Christian Stöveken wrote:
[...]
> after 3 evenigs of fiddling with mostly xorg.conf I just got the first 4
> gpu's / 8 displays working.
Does it mean that you are able to span a single window across 8 
monitors?? If so, could you please send me your xorg.conf??

Thanks in advance for any help.

Greg

Re: videowall

[Ilia Mirkin]

On Wed, Jan 29, 2014 at 8:18 PM, Christian Stöveken
<christian.stoeveken-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> So I had this crazy idea to put together a cheap video wall in my local
> hackerspace using
> a lot of screens suffering from planned obsolescence or at least a poor
> choice in their used caps
> and cheap - used Nvidia NVS 440 cards.
>
> During evaluation of Win 7/8 I noticed there was an 8 gpu OS limit that I
> didn't know of before.
> I also ran into that limt using the proprietary nvidia driver on Linux.
>
> So now I'm trying to see how far nouveau is in regards to "multiple" gpu's
> and
> after 3 evenigs of fiddling with mostly xorg.conf I just got the first 4
> gpu's / 8 displays working.
>
> I'm stuck on the 3rd card / gpu 5+6 / monitors 9-12.
>
> Without spending another few evenings I thought I might check in with you
> guys first whether
> you think it's possible driving a 6400x4096 video wall with nouveau
> and 5 Nvidia NVS 440 cards (NV43) (10 gpus with dual head) - if not I might
> be willing to donate
> the cards for development if someone is interested.

Admittedly I've never tried this, but I can't think of anything that
would prevent you from doing this using the ZaphodHeads/Xinerama
approach. Take a look at
http://nouveau.freedesktop.org/wiki/MultiMonitorDesktop/ -- pay
special attention to the highly-unintuitive Screen setting inside of
the Device section -- it appears to be the index of the crtc to be
used on that device, not the overall screen number (so it just repeats
0/1/0/1/etc). Note that ZaphodHeads was broken for some number of
revisions of xf86-video-nouveau, but it should be all better now - if
you're getting crashes, try upgrading to the latest.

Perhaps you can share your non-working configuration and Xorg log?

Further, there should _definitely_ not be any issues running each
GPU's in a separate X screen and then using some sort of fanciness to
link it all together (e.g. dmx at which point it can all be on
separate machines).

  -ilia

Re: videowall

[Dave Airlie]

On Fri, Jan 31, 2014 at 7:24 AM, Ilia Mirkin <imirkin-FrUbXkNCsVf2fBVCVOL8/A@public.gmane.org> wrote:
> On Wed, Jan 29, 2014 at 8:18 PM, Christian Stöveken
> <christian.stoeveken-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> So I had this crazy idea to put together a cheap video wall in my local
>> hackerspace using
>> a lot of screens suffering from planned obsolescence or at least a poor
>> choice in their used caps
>> and cheap - used Nvidia NVS 440 cards.
>>
>> During evaluation of Win 7/8 I noticed there was an 8 gpu OS limit that I
>> didn't know of before.
>> I also ran into that limt using the proprietary nvidia driver on Linux.
>>
>> So now I'm trying to see how far nouveau is in regards to "multiple" gpu's
>> and
>> after 3 evenigs of fiddling with mostly xorg.conf I just got the first 4
>> gpu's / 8 displays working.
>>
>> I'm stuck on the 3rd card / gpu 5+6 / monitors 9-12.
>>
>> Without spending another few evenings I thought I might check in with you
>> guys first whether
>> you think it's possible driving a 6400x4096 video wall with nouveau
>> and 5 Nvidia NVS 440 cards (NV43) (10 gpus with dual head) - if not I might
>> be willing to donate
>> the cards for development if someone is interested.
>
> Admittedly I've never tried this, but I can't think of anything that
> would prevent you from doing this using the ZaphodHeads/Xinerama
> approach. Take a look at
> http://nouveau.freedesktop.org/wiki/MultiMonitorDesktop/ -- pay
> special attention to the highly-unintuitive Screen setting inside of
> the Device section -- it appears to be the index of the crtc to be
> used on that device, not the overall screen number (so it just repeats
> 0/1/0/1/etc). Note that ZaphodHeads was broken for some number of
> revisions of xf86-video-nouveau, but it should be all better now - if
> you're getting crashes, try upgrading to the latest.

You'll probably run out of PCI address space with too many cards,

Dave.

Fwd: videowall

[Christian Stöveken]

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On Fri, Jan 31, 2014 at 11:25 AM, Dave Airlie <airlied-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
> You'll probably run out of PCI address space with too many cards,
>
> Dave.
>

That could possibly happen - I don't know how to check though.

Looks like the ID's are fine to me.

Could CONFIG_VGA_ARB_MAX_GPUS (is set to 16) be the problem?


xorg.conf_10gpu_20ZH_failstoadd16
https://gist.github.com/excogitation/8755687

Xorg.0.log_10gpu_20ZH_failstoadd16
https://gist.github.com/excogitation/8755639

xorg.conf_8gpu_16_screens_working
https://gist.github.com/excogitation/8755668

Xorg.0.log_8gpu_16_screens_working
https://gist.github.com/excogitation/8755656

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Re: Fwd: videowall

[Stéphane Marchesin]

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On Sat, Feb 1, 2014 at 9:45 AM, Christian Stöveken <
christian.stoeveken-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On Fri, Jan 31, 2014 at 11:25 AM, Dave Airlie <airlied-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>>
>> You'll probably run out of PCI address space with too many cards,
>>
>> Dave.
>>
>
> That could possibly happen - I don't know how to check though.
>
> Looks like the ID's are fine to me.
>
> Could CONFIG_VGA_ARB_MAX_GPUS (is set to 16) be the problem?
>

This problem happens way before the kernel starts. When the bios sets up
the pci resource space, you have something between 512M and 2GB available
for pci resources (this depends on the bios). Each card will usually eat
128M or 256M of pci resource space (although it depends on the cards) so
it's possible to run out. When that happens, some bioses won't boot, others
will just disable some devices. You can look for that info in your kernel
logs, the e820 area size is printed (look for something like e820: [mem
0xd0000000-0xffefffff] available for PCI devices). You can use lspci -v to
check if all the cards come up with their pci resources and how things fit
in there. If all of them have a pci resource then you're fine on that front.

Stéphane

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