On Wed, Jul 04, 2012 at 01:16:14PM -0500, Jonathan Nieder wrote:
> Jonathan Nieder wrote:
> > Luis R. Rodriguez wrote:
>
> >> FWIW we already provide daily backports of code through compat-wireless.
> >> compat-wireless will eventually be changed to "compat-drivers" to reflect
> >> that it has drivers backported other than 802.11. We also have stable
> >> releases
> >> of the Linux kernel backported for use on older releases.
> >
> > I looked at the relevant repositories and am afraid I am too dim to
> > see how to use them.
>
> Ok, it's becoming a little clearer now. Is the appropriate procedure
> something like this?
>
> git clone git://github.com/mcgrof/compat.git
> git clone git://github.com/mcgrof/compat-wireless.git
git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
git clone git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> cd compat-wireless
> git checkout linux-3.0.y
> GIT_COMPAT_TREE=$(pwd)/compat/
this ones always assumes $HOME/compat so if you have it there
already there is no need to specify this variable.
> NEXT_TREE=/path/to/src/linux
> GIT_TREE=/path/to/linux/repo
> export GIT_TREE GIT_COMPAT_TREE
Nope,
export GIT_TREE=/home/foo/linux-stable.git
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
I use Greg's linux-stable.git so I can use all the
extra version stable kernels, but on top of that I have
a remote set up to also pull in Linus' junk:
[remote "linus"]
fetch = +refs/heads/*:refs/remotes/origin/*
url = git://github.com/torvalds/linux.git
So I just do this on linux-stable:
git fetch linus
git reset --hard origin
Then I get reset --hard v3.5-rc5 given that Linus will typically
have a delta on top of the latest RC.
> scripts/gen-stable-release.sh <some appropriate arguments>
The arguments allows you to specify which delta you want to
suck in, if at all.
http://wireless.kernel.org/en/users/Download/stable/#Legend
http://wireless.kernel.org/en/users/Download/stable/#Additional_patches_to_stable_releases
> And then this will not generate a list of patches but just a patched
> source code tree with appropriate #ifdefs to make the code build
> against old kernels.
#ifdef'ing around code to provide kernel backporting is a strategy
of the stone age. We have taken a slightly different approach, we
have stuffed as much into a module / headers: compat.git so that the
code can remain as pristine as possible. This also means that you can
backport *more* subsystems with less effort and I've proven this through
a graph which shows the overhead cost of backporting a new subsystem
once you have a lot of code within a shared compat module:
https://docs.google.com/presentation/d/1axVNEGwKZjnzG1ocdd289WMqPxzJ3qfMv70ghGcnUKc/edit
The only #ifdef crap needed really would then just be things that *cannot* be
backported through a module / headers. In turn we've been discovering that some
of this #ifdef'able stuff actually can be represented also using SmPL and that
this SmPL actually represents collateral evolutions of the Linux kernel. So
the patches/ directory represents just this: collateral evolutions of the Linux
kernel. I've started to formally document this slowly. The first one is the
patch with 4 digits:
patches/0001-netdev_ops.patch
Jesper Andersen however has written a tool called spdiff which I intend
on using to extract SmPL *from* a patch file ! What this means is if
one collateral evolution *which could not be backported through compat.git*
is backported for *two drivers* it means that we can backport that collateral
evolution for *all drivers*. Furthermore if we design collateral evolutions
on the Linux kernel *with* SmPL it means we also can backport that respective
collateral evolution with the *inverse* of SmPL !
> That sounds useful.
How about with all the other junk I just mentioned ? :)
I should mention that stable releases are already made:
http://wireless.kernel.org/en/users/Download/stable/
But surely you can also just make your own as well. The stable releases
also are test compiled accross 21 kernels, and soon, thanks to Ozan's
GSoC project I hope we'll have video backported as well.
Luis
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