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Old 05-08-2011, 11:01 PM
"Boyd Stephen Smith Jr."
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

In <201105081209.28976.bss@iguanasuicide.net>, Boyd Stephen Smith Jr. wrote:
>In <20110508080807.GC7081@think.nuvreauspam>, Andrei Popescu wrote:
>>And nouveau?
>
>I'll give Nouveau a chance sometime this week.

It's definitely got some rough edges. AIXGL is disabled in the Squeeze
version because the experimental mesa library is only in testing/Sid. So,
desktop effects are slow or not present at all. The it's-not-a-benchmark
glxgears benchmark gives a horrible 17 FPS on my large monitor.

Trying to use the testing/Sid version of mesa resulted in a broken X for me.
Seems to be some DRM interface incompatibility with the Squeeze kernel, I
think. I will try this again eventually, but my current solution was to risk
a downgrade of about a dozen packages.

Testing/Sid kernels are broken for me as btrfs dies on both those kernels (see
earlier in thread for bug numbers). So, I can't really test acceleration
there. If it is a DRM incompatibility, I won't be able to get acceleration on
the Squeeze kernel. That basically leaves the -rc5 kernel from experimental,
and I'm just not sure about using an -rc on my daily use machine.

BTW, anyone know how to request that the non-X virtual terminals not use the
framebuffer? It looks quite weird with my setup, so I'd prefer text mode VTs
for the most part.

I'll stick with Nouveau for now, but there are definitely going to be use
cases for me that require going back to the proprietary NVidia module. (E.g.
StarCraft II against my roommate.) It's rather unfortunate that they don't
play together well in kernel space -- switching between them tends to involve
fiddling with /etc/modprobe.d and rebuilding my initramfs(es).

I really should just find a cheap AMD/ATI card that is well supported by Free
Software.

I'm off to experiment some more and see if I can get accelerated nouveau
working on something. I guess even the testing/Sid kernels are worth another
attempt. I won't have the nvidia kernel module tainting the kernel so which
will be an advantage for debugging even if the crash still occurs.
--
Boyd Stephen Smith Jr. ,= ,-_-. =.
bss@iguanasuicide.net ((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-'
http://iguanasuicide.net/ \_/
 
Old 05-09-2011, 02:18 AM
Stephen Powell
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

On Sun, 08 May 2011 19:01:00 -0400 (EDT), Boyd Stephen Smith Jr. wrote:
>
> BTW, anyone know how to request that the non-X virtual terminals not use the
> framebuffer? It looks quite weird with my setup, so I'd prefer text mode VTs
> for the most part.

I don't think that's possible. If you use the nouveau driver in X, you must
use the framebuffer for text virtual consoles. However, there are ways to configure
things to give your text virtual consoles (vt1-vt6) a more normal "look and feel".
By default, it uses the same timings for both text and graphics mode. So,
for example, if your X server uses a 1024x768 graphics mode, your regular vts
will use a 128x48 text console. (1024/8 = 128, 768/16 = 48.) But you can override
that by using the "video" kernel boot parameter. For example,

video=VGA-1:640x400@70

(assuming a CRT monitor). This will give you a standard 80x25 text console
(640/8 = 80, 400/16 = 25). The down side is those annoying KMS messages
every time you switch modes. There's probably a way to suppress them, but I
haven't bothered to figure out how yet.

In my case, my monitor requires an interlaced mode, and interlaced modes
don't work at all with nouveau; so I've been forced to go back to the nv
driver. (The problem seems to be on the kernel side, however, not in the
nouveau X driver itself.)

--
.'`. Stephen Powell
: :' :
`. `'`
`-


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Old 05-09-2011, 05:45 AM
"Boyd Stephen Smith Jr."
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

In <784041656.444588.1304907525303.JavaMail.root@md01 .wow.synacor.com>,
Stephen Powell wrote:
>On Sun, 08 May 2011 19:01:00 -0400 (EDT), Boyd Stephen Smith Jr. wrote:
>> BTW, anyone know how to request that the non-X virtual terminals not use
>> the framebuffer? It looks quite weird with my setup, so I'd prefer text
>> mode VTs for the most part.
>
>I don't think that's possible. If you use the nouveau driver in X, you must
>use the framebuffer for text virtual consoles. However, there are ways to
>configure things to give your text virtual consoles (vt1-vt6) a more normal
>"look and feel". By default, it uses the same timings for both text and
>graphics mode. So, for example, if your X server uses a 1024x768 graphics
>mode, your regular vts will use a 128x48 text console. (1024/8 = 128,
>768/16 = 48.) But you can override that by using the "video" kernel boot
>parameter. For example,
>
> video=VGA-1:640x400@70
>
>(assuming a CRT monitor). This will give you a standard 80x25 text console
>(640/8 = 80, 400/16 = 25)

The problem I am having is a bit more subtle. The framebuffer completely
fills my 19" monitor, but the framebuffer has gaps on the bottom and right of
my 24" monitor. Both are connected to the same physical card.

In text mode, both monitors are completely filled, the text on the 19" is
simply smaller.

I wonder why KMS can't switch between a framebuffer mode and a text mode.
80x24 text mode is a part of the VESA standard, IIRC.

I guess I'll look into kernel / module parameters.
--
Boyd Stephen Smith Jr. ,= ,-_-. =.
bss@iguanasuicide.net ((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-'
http://iguanasuicide.net/ \_/
 
Old 05-09-2011, 05:57 AM
"Boyd Stephen Smith Jr."
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

In <201105081801.00768.bss@iguanasuicide.net>, Boyd Stephen Smith Jr. wrote:
>I'm off to experiment some more and see if I can get accelerated nouveau
>working on something. I guess even the testing/Sid kernels are worth
>another attempt. I won't have the nvidia kernel module tainting the
>kernel so which will be an advantage for debugging even if the crash still
>occurs.

2.6.32 still fails when using the mesa version that has nouveau acceleration.
Still something DRM/DRI related. Quite unfortunate.

2.6.38 (Sid) kernel panics due to an MCE thrown from somewhere in the nouveau
kernel module after switching to the framebuffer. This is before I can get a
console, so it's pretty hard to capture the associated trace; I may be able to
get a USB-to-Serial and a Null-Modem cable this week in order to capture the
requisite information for a bug report.

2.6.38 (Backports), 2.6.39-rc5 (experimental), and 2.6.39-rc6 (experimental)
also exhibit the same behavior as 2.6.38 (Sid), although the backtrace is
slightly different as far as I can tell.

So, at least on my hardware, if you want to use nouveau, you have to forgo any
type of acceleration AND you must use the kernel from stable. For me, this
likely means switching back to the NVidia driver eventually. First, I'd like
to get these bugs filed. Even after that, I will likely hold out until
there's a new linux-kbuild package in Sid; at that point I will want to test
out btrfs on the new kernel.
--
Boyd Stephen Smith Jr. ,= ,-_-. =.
bss@iguanasuicide.net ((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-'
http://iguanasuicide.net/ \_/
 
Old 05-10-2011, 01:52 AM
Stephen Powell
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

On Mon, 09 May 2011 01:45:33 -0400 (EDT), Boyd Stephen Smith Jr. wrote:
>
> The problem I am having is a bit more subtle. The framebuffer completely
> fills my 19" monitor, but the framebuffer has gaps on the bottom and right of
> my 24" monitor. Both are connected to the same physical card.

Are these two monitors connected simultaneously? If so, you need to specify
the "video" kernel boot parameter twice, once for each connector.
See the boot messages for the connector names (i.e. VGA-1 & VGA-2 or
VGA-1 & DVI-I-1, etc.)

Also, keep in mind that a fixed-resolution display, such as an LCD display,
will probably use only a portion of the screen if the resolution specified
is not the maximum supported. A traditional CRT monitor does not generally
act that way.

>
> I wonder why KMS can't switch between a framebuffer mode and a text mode.
> 80x24 text mode is a part of the VESA standard, IIRC.

Good question. I'm not sure. Perhaps they wanted to speed up transitions
between virtual consoles. Perhaps they wanted more flexibility in text modes.
I don't know.
>
> I guess I'll look into kernel / module parameters.

A good place to start is

http://nouveau.freedesktop.org/wiki/KernelModeSetting

--
.'`. Stephen Powell
: :' :
`. `'`
`-


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Old 05-11-2011, 05:35 AM
"Boyd Stephen Smith Jr."
 
Default Nouveau Experiments (was: grub-probe: error: cannot stat `/dev/root')

On 2011-05-09 20:52:05 Stephen Powell wrote:
>On Mon, 09 May 2011 01:45:33 -0400 (EDT), Boyd Stephen Smith Jr. wrote:
>> The problem I am having is a bit more subtle. The framebuffer completely
>> fills my 19" monitor, but the framebuffer has gaps on the bottom and right
>> of my 24" monitor. Both are connected to the same physical card.
>
>Are these two monitors connected simultaneously?

Yes.

>If so, you need to specify
>the "video" kernel boot parameter twice, once for each connector.
>See the boot messages for the connector names (i.e. VGA-1 & VGA-2 or
>VGA-1 & DVI-I-1, etc.)

For me, It DVI-I-1 and DVI-I-2.

> http://nouveau.freedesktop.org/wiki/KernelModeSetting

Thanks for the pointers.
--
Boyd Stephen Smith Jr. ,= ,-_-. =.
bss@iguanasuicide.net ((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-'
http://iguanasuicide.net/ \_/
 

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