The difference between Linus's kernel and Alan Cox's kernel

The difference between Linus's kernel and Alan Cox's kernel

[Thiago Vinhas de Moraes]

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Hi.

Maybe lots of you already know the answer, maybe it's a really stupid 
question. If it is, please tell me. I'll not be offended.

Why there are two different kernel trees? There is always the official 
release, provided by Torvalds, and then Alan provides a patch merging Linus's 
stuff, and adding (?) tons of bug fixes.

Why aren't the -ac patches completely merged to the official tree, and you 
centralize the work on single kernel patches ?? Won't it be easier to 
administrate?

I'm so sorry if it's a really stupid question. It's because I never know what 
pre-patch to apply, the -ac* or the -pre*. In doubt, I apply Alan's, because 
it appears to be always Linus stuff, and more bug fixes, recently, the 
Linus's -pre* appears to have merges from the -ac on each release.
I just don't understand why it can all be merged.


Regards,
Thiago Vinhas de Moraes
NetWorx - A SuaCompanhia.com
Rio de Janeiro - Brazil
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Re: The difference between Linus's kernel and Alan Cox's kernel

[Wayne.Brown]

It really ought to be Linus and/or Alan who answers this, but from my own
observations, here's the way I think it goes:

Alan and Linus don't always agree on what should be in the kernel; and even when
they do, they sometimes disagree on when something is ready to be included.
Alan may think a particular set of patches are ready, while Linus thinks they
need to mature a bit more; or perhaps he thinks the whole approach is wrong and
should be scrapped.  So Alan puts it in his kernel, and Linus leaves it out of
his.  (Of course, sometimes it's Linus who adds something that Alan rejects.)
It sometimes happens that one of these new ideas turns out better than expected
(especially after going through a few bug report/new patch cycles), and the
person who rejected it changes his mind and includes it later; or maybe it
doesn't work out and gets dropped altogether.  Also, as you've already observed,
Alan regularly resyncs major parts of his tree with Linus' so they don't get too
far apart, and Linus occasionally does the same.

It used to bother me, too, to have to keep up with two different kernel trees.
But I've come to realize that this is a Good Thing.  It provides a way for
people with different viewpoints to approach an idea from more than one
direction.  If the two kernels are trying to solve a particular problem in
different ways, we get to see how each approach works in the real world, rather
than just in a theoretical discussion.  If the two kernels branch too far apart
it could be a problem, but Linus and Alan have been diligent about keeping that
from happening.  I think the interplay (is "competition" too strong a word?)
between the two branches has helped make the "official" kernel better than it
might have been otherwise.

Wayne

Re: The difference between Linus's kernel and Alan Cox's kernel

[Erik Mouw]

On Fri, May 25, 2001 at 05:12:39PM -0300, Thiago Vinhas de Moraes wrote:
> Why there are two different kernel trees? There is always the official 
> release, provided by Torvalds, and then Alan provides a patch merging Linus's 
> stuff, and adding (?) tons of bug fixes.

I just added this to the kernelnewbies FAQ:

  http://www.kernelnewbies.org/faq.php3


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
of Electrical Engineering, Faculty of Information Technology and Systems,
Delft University of Technology, PO BOX 5031,  2600 GA Delft, The Netherlands
Phone: +31-15-2783635  Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/

Re: The difference between Linus's kernel and Alan Cox's kernel

[CaT]

On Fri, May 25, 2001 at 11:32:18PM +0200, Erik Mouw wrote:
> On Fri, May 25, 2001 at 05:12:39PM -0300, Thiago Vinhas de Moraes wrote:
> > Why there are two different kernel trees? There is always the official 
> > release, provided by Torvalds, and then Alan provides a patch merging Linus's 
> > stuff, and adding (?) tons of bug fixes.
> 
> I just added this to the kernelnewbies FAQ:
> 
>   http://www.kernelnewbies.org/faq.php3

Typo: First para, last sentence: s/Linux/Linus/

-- 
CaT (cat@zip.com.au)		*** Jenna has joined the channel.
				<cat> speaking of mental giants..
				<Jenna> me, a giant, bullshit
				<Jenna> And i'm not mental
					- An IRC session, 20/12/2000

Re: The difference between Linus's kernel and Alan Cox's kernel

[Erik Mouw]

On Sat, May 26, 2001 at 07:40:18AM +1000, CaT wrote:
> On Fri, May 25, 2001 at 11:32:18PM +0200, Erik Mouw wrote:
> > I just added this to the kernelnewbies FAQ:
> > 
> >   http://www.kernelnewbies.org/faq.php3
> 
> Typo: First para, last sentence: s/Linux/Linus/

Oops. Fixed, thanks.


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
of Electrical Engineering, Faculty of Information Technology and Systems,
Delft University of Technology, PO BOX 5031,  2600 GA Delft, The Netherlands
Phone: +31-15-2783635  Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/

Re: The difference between Linus's kernel and Alan Cox's kernel

[Alan Cox]

> Why there are two different kernel trees? There is always the official 
> release, provided by Torvalds, and then Alan provides a patch merging Linus's 
> stuff, and adding (?) tons of bug fixes.

Well it started by accident but it turns out good to have a tree that changes
are merged into, tested by those who need the fixes and reviewed by third
parties before they go to Linus.

So the -ac tree is kind of a peer review, testing and distillation process for
patches.

Re: The difference between Linus's kernel and Alan Cox's kernel

[Thiago Vinhas de Moraes]

Em Sex 25 Mai 2001 20:05, Alan Cox escreveu:
> > Why there are two different kernel trees? There is always the official
> > release, provided by Torvalds, and then Alan provides a patch merging
> > Linus's stuff, and adding (?) tons of bug fixes.
>
> Well it started by accident but it turns out good to have a tree that
> changes are merged into, tested by those who need the fixes and reviewed by
> third parties before they go to Linus.
>
> So the -ac tree is kind of a peer review, testing and distillation process
> for patches.

But will this happen forever? You (Alan) is currently the maintaner of the 
2.2 tree. Won't you be going to assume the 2.4 tree, while the 2.5 series 
development starts?

BTW, Thanks for your answer.

Regards,
-- 
________________________________
 Thiago Vinhas de Moraes
 NetWorx - A SuaCompanhia.com