[linux-yocto] [PATCH 0/2] NTB & IOATDMA features for v3.8 kernel repo

[Kamble, Nitin A]

> -----Original Message-----
> From: Bruce Ashfield [mailto:bruce.ashfield at windriver.com]
> Sent: Friday, March 01, 2013 9:07 PM
> To: Kamble, Nitin A
> Cc: linux-yocto at yoctoproject.org
> Subject: Re: [PATCH 0/2] NTB & IOATDMA features for v3.8 kernel repo
> 
> On 13-03-01 8:05 PM, nitin.a.kamble at intel.com wrote:
> > From: Nitin A Kamble<nitin.a.kamble at intel.com>
> >
> > Hi Bruce,
> >     I have prepared commits for enabling non-transparent-bridge and
> > Crystal-Beach-DMA/DCA drivers in the kernel.
> >
> > This is needed to implement features in this bug:
> >     https://bugzilla.yoctoproject.org/show_bug.cgi?id=2465
> >
> > I have created a new "ntb" git branch for the ntb feature. The branch is
> pushed here:
> >
> > http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-contrib/log/?h=n
> > itin/ntb
> >
> > As it is a new branch for kernel repo, I am not sending individual commits
> over ML.
> > You can directly fetch the ntb branch in the v3.8 repo.
> >
> > And new features for ioatdma (aka Crystal Beach DMA/DCA)&  ntb (non
> > transparent bridge) are created in the meta branch over here:
> >
> > http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-contrib/log/?h=n
> > itin/meta
> 
> Nitin,
> 
> In general this looks pretty good. I've been tracking NTB development for
> quite some time, so luckily I'm aware of the challenges working with the
> feature.
> 
> Just a few questions.
> 
>     - I assume this has passed build tests ?
> 
>     - Who's doing the NTB runtime testing ? I've seen this code in the past,
>       and while it builds relatively easily .. getting it tested is more
>       of a challenge.
> 
> And a request .. I realize that this wouldn't have been obvious when you
> were working on this, but that's what the mailing list review is for!
> 
> This feature in particular shouldn't be staged as a branch and merged, so just
> set it up as a .scc file (as you have it) without the patches. If you want the
> patches to be applied whenever ntb-common.scc is included, let me know
> and that's where I'll place them. I'll then merge these changes to the
> standard/base branch to make them available to all BSPs.
> 
> You are probably wondering why it shouldn't be a topic branch and merged.
> The reason comes down to the fact that it will conflict with both mainline
> development and BSP work. This is an active area of development (and
> hence bug fixing as well), so the chances of a topic branch conflicting and
> failing to merge are high. I'll need to resolve those conflicts in tree while
> stacking patches, I can't do that with a topic branch.
> 
> Features that usually get a topic branch are:
> 
>    - features that are largely developed out of tree
>    - features that are orthogonal to other code in the tree, and don't
>      touch many common files
>    - features that may have active development, where we want to track
>      the history separately (versus patch based history) or we want to
>      track a significant amount of commits.
>    - features that will update/upgrade and migrate over time.
>    - "just because" :)
> 
> With that set of criteria, things like graphics drivers (emgd, or schedulers
> (EDF)) get topic branches. But other features like preempt-rt (it will always
> conflict) or lttng-1.x don't get topic branches. And that's why ntb really
> shouldn't have one either. IF we have to many topic branches, we'll end up
> with patch time merge failures of the topic branches .. which are difficult to
> resolve.
> 
> It should be a simple thing to re-order (since the content is all largely the
> same) .. and will take less time that I did typing all this up :)
> 
> Cheers,
> 
> Bruce

Hi Bruce,
   Thanks for explaining the process to me. I understand and agree with
 the reason of putting these bits in the base branch. This pull request from
me was  more of a RFC.
  I will do some more build testing with the new layout of commits. And send
 another pull for this.

Thanks,
Nitin


> 
> 
> >
> > Thanks,
> > Nitin
> >
> > The following changes since commit
> c2ed0f16fdec628242a682897d5d86df4547cf24:
> >
> >    checkpoint dir: meta (2013-02-24 22:43:59 -0500)
> >
> > are available in the git repository at:
> >    git://git.yoctoproject.org/linux-yocto-contrib nitin/meta
> >
> > http://git.yoctoproject.org/cgit.cgi/linux-yocto-contrib/log/?h=nitin/
> > meta
> >
> > Nitin A Kamble (2):
> >    new feature for non-transparent-bridge driver
> >    new feature for I/OAT DMA driver
> >
> >   meta/cfg/kernel-cache/features/ioatdma/ioatdma.cfg |    1 +
> >   meta/cfg/kernel-cache/features/ioatdma/ioatdma.scc |    1 +
> >   meta/cfg/kernel-cache/features/ntb/ntb.cfg         |    1 +
> >   meta/cfg/kernel-cache/features/ntb/ntb.scc         |    2 ++
> >   4 files changed, 5 insertions(+), 0 deletions(-)
> >   create mode 100644 meta/cfg/kernel-
> cache/features/ioatdma/ioatdma.cfg
> >   create mode 100644 meta/cfg/kernel-
> cache/features/ioatdma/ioatdma.scc
> >   create mode 100644 meta/cfg/kernel-cache/features/ntb/ntb.cfg
> >   create mode 100644 meta/cfg/kernel-cache/features/ntb/ntb.scc
> >