Bug#790694: PPC64: 64kb kernel pagesizes and nouveau

[Vincent Pelletier]

Hello,

nouveau still does not support 64k pages, so I believe this bug is
still current.

It may not be the only one active on PPC64BE though: having built a
vanilla 4.11.5 using debian's 4.11 config and changing to 4k pages is
sadly not enough to make X work on a Powermac G5 ("late 2005" model)
with NV47.

The most visible aspect of the issue is similar in both 64k and 4k
pages: after a cold boot, there is a narrow solid grey rectangle from
screen top-left corner along top border which width seems to depend on
page size, and under it random noise in large vertical rectangles with
varying dominant hue (mostly white, mostly black, mostly cyan and mostly
magenta). After a warm reboot from OSX, elements of its GUI are
visible instead of these hue, with the same amount of random noise
added over it.

The dynamic effects are that once X has been started, chvt blocks (so
there is no going back to text mode), and X takes a long while to die
(several minutes) which also affects reboots and shutdown (maybe systemd
reaching its timeout threshold ?). ssh works fine during that time.

Regards,
-- 
Vincent Pelletier

Bug#790694: PPC64: 64kb kernel pagesizes and nouveau

[Mathieu Malaterre]

Bastian,

On Wed, Mar 30, 2016 at 11:18 PM, Aurelien Jarno  wrote:
> On 2016-03-30 16:45, Ben Hutchings wrote:
>> On Wed, 2016-03-30 at 16:49 +0200, Mathieu Malaterre wrote:
>> > Ben,
>> >
>> > >
>> > > I saw that bug report as well.  I'm not sure what to do about it -
>> > > other distributions were also using 64K pages for 64-bit PowerPC the
>> > > last time I looked, and there may be good reasons to do that.
>> > Would it be possible for you to dig that for us ? It appears that
>> > making nouveau work with 64K page is non-trivial:
>> >
>> > https://bugs.freedesktop.org/show_bug.cgi?id=94757#c3
>> >
>> > Which in turns means most of the userbase with PPC64 (G5 PowerMac)
>> > wont be able to use X.
>>
>> I am not a powerpc porter; Aurelien Jarno is the kernel maintainer
>> responsible for it.
>
> That's correct for ppc64el, but I never signed up for the powerpc port.
>
>> I don't know about the user base, but I think most of the *development*
>> effort and sponsorship of the powerpc ports now comes from IBM, and
>> unfortunately they don't care about PowerMacs.
>
> IBM doesn't really care about the powerpc port either, they do about the
> ppc64el port. That said I have tracked the change to 64kB pages to the
> following commit:
>
> | commit aed63a56b189d771116f2d4b8fe10bbec528e6a2
> | Author: Bastian Blank 
> | Date:   Sat Aug 9 19:42:11 2014 +
> |
> | * debian/changelog: Update
> | * debian/config/kernelarch-powerpc/config-arch-64: Set PPC_64K_PAGES.
> | * debian/config/kernelarch-powerpc/config-arch-64-le: Remove overriden 
> option.
> |
> | svn path=/dists/trunk/linux/; revision=21721
>
> I don't really know what it has been done, so I have Cced Bastian so
> that he can comment on that. It's something that can be reverted if
> needed I guess.

Could you please share the rational to set PPC64 to 64K pages ?

Ref: 
https://anonscm.debian.org/cgit/kernel/linux.git/commit/?id=aed63a56b189d771116f2d4b8fe10bbec528e6a2

Thanks much.

Bug#790694: PPC64: 64kb kernel pagesizes and nouveau

[Aurelien Jarno]

On 2016-03-30 16:45, Ben Hutchings wrote:
> On Wed, 2016-03-30 at 16:49 +0200, Mathieu Malaterre wrote:
> > Ben,
> > 
> > > 
> > > I saw that bug report as well.  I'm not sure what to do about it -
> > > other distributions were also using 64K pages for 64-bit PowerPC the
> > > last time I looked, and there may be good reasons to do that.
> > Would it be possible for you to dig that for us ? It appears that
> > making nouveau work with 64K page is non-trivial:
> > 
> > https://bugs.freedesktop.org/show_bug.cgi?id=94757#c3
> > 
> > Which in turns means most of the userbase with PPC64 (G5 PowerMac)
> > wont be able to use X.
> 
> I am not a powerpc porter; Aurelien Jarno is the kernel maintainer
> responsible for it.

That's correct for ppc64el, but I never signed up for the powerpc port.

> I don't know about the user base, but I think most of the *development*
> effort and sponsorship of the powerpc ports now comes from IBM, and
> unfortunately they don't care about PowerMacs.

IBM doesn't really care about the powerpc port either, they do about the
ppc64el port. That said I have tracked the change to 64kB pages to the
following commit:

| commit aed63a56b189d771116f2d4b8fe10bbec528e6a2
| Author: Bastian Blank 
| Date:   Sat Aug 9 19:42:11 2014 +
|
| * debian/changelog: Update
| * debian/config/kernelarch-powerpc/config-arch-64: Set PPC_64K_PAGES.
| * debian/config/kernelarch-powerpc/config-arch-64-le: Remove overriden 
option.
|
| svn path=/dists/trunk/linux/; revision=21721

I don't really know what it has been done, so I have Cced Bastian so
that he can comment on that. It's something that can be reverted if
needed I guess.

Aurelien

-- 
Aurelien Jarno  GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net


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Bug#790694: PPC64: 64kb kernel pagesizes and nouveau

[Ben Hutchings]

On Wed, 2016-03-30 at 16:49 +0200, Mathieu Malaterre wrote:
> Ben,
> 
> > 
> > I saw that bug report as well.  I'm not sure what to do about it -
> > other distributions were also using 64K pages for 64-bit PowerPC the
> > last time I looked, and there may be good reasons to do that.
> Would it be possible for you to dig that for us ? It appears that
> making nouveau work with 64K page is non-trivial:
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=94757#c3
> 
> Which in turns means most of the userbase with PPC64 (G5 PowerMac)
> wont be able to use X.

I am not a powerpc porter; Aurelien Jarno is the kernel maintainer
responsible for it.

I don't know about the user base, but I think most of the *development*
effort and sponsorship of the powerpc ports now comes from IBM, and
unfortunately they don't care about PowerMacs.

Ben.

-- 
Ben Hutchings
Tomorrow will be cancelled due to lack of interest.

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Bug#790694: PPC64: 64kb kernel pagesizes and nouveau

[Mathieu Malaterre]

Ben,

> I saw that bug report as well.  I'm not sure what to do about it -
> other distributions were also using 64K pages for 64-bit PowerPC the
> last time I looked, and there may be good reasons to do that.

Would it be possible for you to dig that for us ? It appears that
making nouveau work with 64K page is non-trivial:

https://bugs.freedesktop.org/show_bug.cgi?id=94757#c3

Which in turns means most of the userbase with PPC64 (G5 PowerMac)
wont be able to use X.

Thanks for your time,