Starting the arch/powerpc merge

Starting the arch/powerpc merge

[Paul Mackerras]

I have pushed a commit to the powerpc-merge.git tree which gets us far
enough to be able to build a 32-bit powermac kernel with
ARCH=powerpc.  It's still very rough in places, and it uses bits out
of arch/ppc/kernel and arch/ppc/syslib, but it is a start.

Of course, this means that we are about to bump up against the really
hard bits of the merge.  Things like

* converting ppc32 to use the lmb infrastructure
* introducing the device-tree flattening/unflattening to ppc32
* working out how to deal with the early hash table initialization
  that POWER4 needs on ppc32
* reconciling the fact that ppc64 needs RELOC in the prom_init code,
  whereas ppc32 doesn't; but ppc64 doesn't need RELOC when running
  with the MMU off but ppc32 does (or needs -mrelocatable).

I look forward to people sending me patches to push this on a bit
further, and in particular to populate arch/powerpc/platforms a bit
more. :)

Paul.

Re: Starting the arch/powerpc merge

[Kumar Gala]

On Sep 26, 2005, at 7:25 PM, Paul Mackerras wrote:

> I have pushed a commit to the powerpc-merge.git tree which gets us far
> enough to be able to build a 32-bit powermac kernel with
> ARCH=powerpc.  It's still very rough in places, and it uses bits out
> of arch/ppc/kernel and arch/ppc/syslib, but it is a start.
>
> Of course, this means that we are about to bump up against the really
> hard bits of the merge.  Things like
>
> * converting ppc32 to use the lmb infrastructure
> * introducing the device-tree flattening/unflattening to ppc32
> * working out how to deal with the early hash table initialization
>   that POWER4 needs on ppc32
> * reconciling the fact that ppc64 needs RELOC in the prom_init code,
>   whereas ppc32 doesn't; but ppc64 doesn't need RELOC when running
>   with the MMU off but ppc32 does (or needs -mrelocatable).
>
> I look forward to people sending me patches to push this on a bit
> further, and in particular to populate arch/powerpc/platforms a bit
> more. :)

You have duplicated files between arch/ppc/ and arch/powerpc.  Do you  
plan on cleaning this up are should we make sure we "fix" both?

- kumar

Re: Starting the arch/powerpc merge

[Stephen Rothwell]

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On Mon, 26 Sep 2005 22:39:56 -0500 Kumar Gala <kumar.gala@freescale.com> wrote:
>
> You have duplicated files between arch/ppc/ and arch/powerpc.  Do you  
> plan on cleaning this up are should we make sure we "fix" both?

I have done a patch that fixed most of those (but not all).  It will be in the
merge tree when Paulus next pushes it out.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: Starting the arch/powerpc merge

[Christoph Hellwig]

On Tue, Sep 27, 2005 at 10:25:38AM +1000, Paul Mackerras wrote:
> * working out how to deal with the early hash table initialization
>   that POWER4 needs on ppc32

What about just dropping POWER3/4 support in 32bit mode?

Re: Starting the arch/powerpc merge

[Paul Mackerras]

Christoph Hellwig writes:

> What about just dropping POWER3/4 support in 32bit mode?

Yes... I'm getting very close to deciding to do that.  In fact POWER3
isn't too bad, since it still has BATs, but POWER4/PPC970 would be
tricky.

Does anyone on these lists have any major objections if we drop
support for 32-bit kernels on POWER3 and POWER4/PPC970?

Paul.

Re: Starting the arch/powerpc merge

[Heikki Lindholm]

Paul Mackerras kirjoitti:
> Christoph Hellwig writes:
> 
> 
>>What about just dropping POWER3/4 support in 32bit mode?
> 
> 
> Yes... I'm getting very close to deciding to do that.  In fact POWER3
> isn't too bad, since it still has BATs, but POWER4/PPC970 would be
> tricky.
> 
> Does anyone on these lists have any major objections if we drop
> support for 32-bit kernels on POWER3 and POWER4/PPC970?

I think it was Kumar Gala who already asked this a while ago. For me, 
32-bit kernel on a 970 has been useful "initial stage" of gradually 
porting kernel stuff over to real 64-bit, but if I'm the only user and 
keeping the support is a nuisance, go ahead and drop it.

-- Heikki Lindholm

Re: Starting the arch/powerpc merge

[Pantelis Antoniou]

Heikki Lindholm wrote:
> Paul Mackerras kirjoitti:
> 
>> Christoph Hellwig writes:
>>
>>
>>> What about just dropping POWER3/4 support in 32bit mode?
>>
>>
>>
>> Yes... I'm getting very close to deciding to do that.  In fact POWER3
>> isn't too bad, since it still has BATs, but POWER4/PPC970 would be
>> tricky.
>>
>> Does anyone on these lists have any major objections if we drop
>> support for 32-bit kernels on POWER3 and POWER4/PPC970?
> 
> 
> I think it was Kumar Gala who already asked this a while ago. For me, 
> 32-bit kernel on a 970 has been useful "initial stage" of gradually 
> porting kernel stuff over to real 64-bit, but if I'm the only user and 
> keeping the support is a nuisance, go ahead and drop it.
> 
> -- Heikki Lindholm

Count me in too; using a 970 in 32 bit mode, because of gentoo X.org
problems in 64 bit mode.

Regards

Pantelis

Re: Starting the arch/powerpc merge

[Pantelis Antoniou]

Paul Mackerras wrote:
> Pantelis Antoniou writes:
> 
> 
>>Count me in too; using a 970 in 32 bit mode, because of gentoo X.org
>>problems in 64 bit mode.
> 
> 
> I'm using an X.org server on a ppc64 kernel, and it all works,
> including DRI.  Both 32-bit and 64-bit X server and clients work.  We
> now have the 32-bit ioctl compatibility sorted out in the kernel DRM.
> So I don't think X is a reason to run a 32-bit kernel any more.
> 
> What X.org problems do you see with a 64-bit kernel?
> 
> Paul.
> 
> 
> 

I didn't really tried a very recent kernel, I tried it about a month ago,
and it didn't work. Could be a gentoo problem for all I know.

Since I don't have time to debug these kind of problems, it's really nice
to know that it now works :).

No worries then.

Regards

Pantelis

Re: Starting the arch/powerpc merge

[Paul Mackerras]

Pantelis Antoniou writes:

> Count me in too; using a 970 in 32 bit mode, because of gentoo X.org
> problems in 64 bit mode.

I'm using an X.org server on a ppc64 kernel, and it all works,
including DRI.  Both 32-bit and 64-bit X server and clients work.  We
now have the 32-bit ioctl compatibility sorted out in the kernel DRM.
So I don't think X is a reason to run a 32-bit kernel any more.

What X.org problems do you see with a 64-bit kernel?

Paul.

Re: Starting the arch/powerpc merge

[Paul Mackerras]

Kumar Gala writes:

> You have duplicated files between arch/ppc/ and arch/powerpc.  Do you  
> plan on cleaning this up are should we make sure we "fix" both?

I did that deliberately so that I could hack the merged version
without worrying about whether I would break the compile with ARCH=ppc
or ARCH=ppc64.  If it turns out that the merged version of some file
is sufficiently similar to the ppc version, we can then delete the ppc
version and just use the merged version.

Paul.

Re: Starting the arch/powerpc merge

[Daniel Ostrow]

>Pantelis Antoniou writes:
>
>> Count me in too; using a 970 in 32 bit mode, because of gentoo X.org
>> problems in 64 bit mode.
>
>I'm using an X.org server on a ppc64 kernel, and it all works,
>including DRI.  Both 32-bit and 64-bit X server and clients work.  We
>now have the 32-bit ioctl compatibility sorted out in the kernel DRM.
>So I don't think X is a reason to run a 32-bit kernel any more.
>
>What X.org problems do you see with a 64-bit kernel?
>
>Paul.

Speaking as a member of the Gentoo/PPC64 team I'm also curious what
issues you are having...the only open issues that I am aware of have to
do with the recent r7 X.org prereleases...both modular and monolithic.
If that is what you are talking about then yeah there are issues...but
more then likely they are on the X.org side not the kernels. Anything in
the 6.8.2 range (which is what is stable) has been working fine for a
long long time under a pure 64-bit env.

Thanks,

-- 
Daniel Ostrow
Gentoo Foundation Board of Trustees
Gentoo/{PPC,PPC64,DevRel}
dostrow@gentoo.org

Re: Starting the arch/powerpc merge

[Christopher Friesen]

Daniel Ostrow wrote:
> Anything in
> the 6.8.2 range (which is what is stable) has been working fine for a
> long long time under a pure 64-bit env.

What about mixed 32-bit userspace and 64-bit kernel?

Chris

Re: Starting the arch/powerpc merge

[Daniel Ostrow]

On Tue, 2005-09-27 at 10:43 -0600, Christopher Friesen wrote:
> Daniel Ostrow wrote:
> > Anything in
> > the 6.8.2 range (which is what is stable) has been working fine for a
> > long long time under a pure 64-bit env.
> 
> What about mixed 32-bit userspace and 64-bit kernel?
> 
> Chris
> 

The way I set that up is still young...and has some issues (most of
which should be fixed by the ppc && ppc64 -> powerpc merge). From what I
have tested, it does work perfectly fine with 6.8.2...I haven't run into
any issues. I maintain that profile so if there are issues please take
them off this list...feel free to send them to ppc64@gentoo.org or open
a bug at bugs.gentoo.org and assign it to the ppc64 group. I'll see it
either way.

Thanks,

-- 
Daniel Ostrow
Gentoo Foundation Board of Trustees
Gentoo/{PPC,PPC64,DevRel}
dostrow@gentoo.org

Re: Starting the arch/powerpc merge

[Benjamin Herrenschmidt]

On Tue, 2005-09-27 at 18:30 +1000, Paul Mackerras wrote:
> Christoph Hellwig writes:
> 
> > What about just dropping POWER3/4 support in 32bit mode?
> 
> Yes... I'm getting very close to deciding to do that.  In fact POWER3
> isn't too bad, since it still has BATs, but POWER4/PPC970 would be
> tricky.
> 
> Does anyone on these lists have any major objections if we drop
> support for 32-bit kernels on POWER3 and POWER4/PPC970?

I've stopped supporting G5 on 32 bits kernel for some time now, I have
absolutely no problem just dropping the POWER4 support in 32 bits kernel
in the merged tree.

Ben.

Re: Starting the arch/powerpc merge

[Benjamin Herrenschmidt]

> The way I set that up is still young...and has some issues (most of
> which should be fixed by the ppc && ppc64 -> powerpc merge). From what I
> have tested, it does work perfectly fine with 6.8.2...I haven't run into
> any issues. I maintain that profile so if there are issues please take
> them off this list...feel free to send them to ppc64@gentoo.org or open
> a bug at bugs.gentoo.org and assign it to the ppc64 group. I'll see it
> either way.

I'm running a 32 bits X.org 6.8.99 from CVS with the r300 DRI stuff
etc... on a G5 with 64 bits kernel without trouble. Paulus did the same
with a 64 bits X.

Ben.

Re: Starting the arch/powerpc merge

[Giuliano Pochini]

On 28-Sep-2005 Benjamin Herrenschmidt wrote:
> On Tue, 2005-09-27 at 18:30 +1000, Paul Mackerras wrote:
>> Christoph Hellwig writes:
>>
>> > What about just dropping POWER3/4 support in 32bit mode?
>>
>> Yes... I'm getting very close to deciding to do that.  In fact POWER3
>> isn't too bad, since it still has BATs, but POWER4/PPC970 would be
>> tricky.
>>
>> Does anyone on these lists have any major objections if we drop
>> support for 32-bit kernels on POWER3 and POWER4/PPC970?
>
> I've stopped supporting G5 on 32 bits kernel for some time now, I have
> absolutely no problem just dropping the POWER4 support in 32 bits kernel
> in the merged tree.

Out of curiosity, is there any advantage in using a 32 bits
kernel on ppc64 over a 64 bits kernel ?  Speed ?  Complexity ?
Compatibility ?  Memory ?



--
Giuliano.

Re: Starting the arch/powerpc merge

[Paul Mackerras]

Giuliano Pochini writes:

> Out of curiosity, is there any advantage in using a 32 bits
> kernel on ppc64 over a 64 bits kernel ?  Speed ?  Complexity ?
> Compatibility ?  Memory ?

Not really.  The main thing in the past has been that DRI with 32-bit
X server and clients would work with a 32-bit kernel but not a 64-bit
kernel, but that's fixed now.  A 64-bit kernel is faster on most
lmbench tests.  I guess a 32-bit kernel might end up a little smaller,
but that's the only possible advantage I can think of.

Paul.

Re: Starting the arch/powerpc merge

[Paul Mackerras]

I wrote:

> Not really.  The main thing in the past has been that DRI with 32-bit
> X server and clients would work with a 32-bit kernel but not a 64-bit
> kernel, but that's fixed now.  A 64-bit kernel is faster on most
> lmbench tests.  I guess a 32-bit kernel might end up a little smaller,
> but that's the only possible advantage I can think of.

Oops, sorry, mail system breakage here...

Paul.

Re: Starting the arch/powerpc merge

[Giuliano Pochini]

On 06-Oct-2005 Paul Mackerras wrote:

>> Out of curiosity, is there any advantage in using a 32 bits
>> kernel on ppc64 over a 64 bits kernel ?  Speed ?  Complexity ?
>> Compatibility ?  Memory ?
>
> Not really.  The main thing in the past has been that DRI with 32-bit
> X server and clients would work with a 32-bit kernel but not a 64-bit
> kernel, but that's fixed now.  A 64-bit kernel is faster on most
> lmbench tests.  I guess a 32-bit kernel might end up a little smaller,
> but that's the only possible advantage I can think of.

And 32<->64 bits compatibility layer for 32bits apps is not needed,
so maybe they run a bit faster. Well, at this point IMHO 32-on-64
support may be dropped without regrets. Spending time for an useless
thing is - uhm - useless.


> Oops, sorry, mail system breakage here...

My mail wasn't important anyway :))


--
Giuliano.