[CentOS-devel] CentOS Plus: Valuable or wasted resource?

Johnny Hughes johnny at centos.org
Fri Sep 11 13:05:59 UTC 2009


On 09/10/2009 11:11 AM, Akemi Yagi wrote:
> On Thu, Sep 10, 2009 at 7:59 AM, Tim Verhoeven
> <tim.verhoeven.be at gmail.com> wrote:
>> On Thu, Sep 10, 2009 at 4:24 PM, Ross Walker <rswwalker at gmail.com> wrote:
>>> Is CentOS Plus really necessary?
>>>
>>> The reason I ask is it seems it is there to provide additional kernel
>>> modules not included in the base repo that could be added to 'extras'
>>> as kmods.
>>> Let outside repos provide custom kernels.
> 
>> First, the CentOSPlus is more then just the modified kernel. Stuff
>> like the RHWAS stuff will also end up in CentOSPlus when its released.
>> It is basically a place where we put all things that conflict with the
>> things in the base OS repo.
> 
> Yes. I'm sure Ross meant just the centosplus kernel, not the
> centosplus repository.
> 
>> Secondly, the kernel itself is maintained by Akemi who is also part of
>> the Elrepo team that builds kmods. So you can choose between
>> installing kmod or using the centosplus kernel. And there are thing
>> done in the centosplus kernel that can't be done using kmods. But I
>> will let Akemi fill in the details.
> 
> I have been helping with the maintenance of centosplus kernels for
> about a year. And yes, I am involved in the ELRepo project as well (I
> must admit that most of crucial works are the results of other
> members' contributions).
> 
> [OT] Just to defend myself ... I supply the src.rpm for the cplus
> kernel usually within 24 hours for each kernel update. "is always
> behind" may be a bit misleading ... :-)  [/OT]
> 
> As Tim mentioned, enabling certain options for additional device
> support is not the only thing cplus kernels offer.  There are patches
> that are applied which cannot be done in the distro kernels.  For
> example, there are currently 4 patches in the cplus kernel. Two of
> them will be in the upcoming CentOS 5.4.
> 
> I think that many, if not all, of the kernel drivers enabled in the
> cplus kernel can / will be replaced by kABI-tracking kmods.  In fact,
> Alan Bartlett made a list of such modules some time ago.  At this
> moment, kmods for ntfs, ufs, jfs, reiserfs, and video4linux are
> available from ELRepo.
> 
>> So, the same person doing the CentOSPlus kernel is also doing kmods.
>> There is no waist of resources :-)
> 
> Indeed, my _waist_ is just fine.  :-P

Aside from Akemi's waist ... one other very important point that she
makes is that for several of the plus kernels at several points in time
there are patches applied to fix things that are not fixed yet upstream
and that we can not fix in the main line kernels (as we do not apply
patches to those).

These patches can be for things like a drbd performance, NFS issues, etc.

They are normally in the upstream testing process/bugzilla, but can
sometimes take months to fix (or never be fixed ... like NTFS in the 5.x
kernel, we are not patching that now, but might later) upstream.

I am also a bit hesitant in producing kABI type kernels for CentOS-4 as
there is no tracking mechanism to require the correct version of each of
the base kernel requires as there is in CentOS-5, so weak updates can
create problems for users in CentOS-4.  I am OK with that for things
outside the main kernel, but for things that are part of the included
kernel, I am more hesitant.

I do like the fact that these are also in ELrepo and give users another
option for installation if they want to go that route.


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