[CentOS] RFI: Information for Centos 4 unsupported kernels

Wed Jun 21 13:57:15 UTC 2006
Johnny Hughes <mailing-lists at hughesjr.com>

On Wed, 2006-06-21 at 08:15 -0400, William L. Maltby wrote:
> On Wed, 2006-06-21 at 05:47 -0500, Johnny Hughes wrote:
> > On Tue, 2006-06-20 at 22:32 +0300, Kari Salovaara wrote:
> > > Hi,
> > > 
> > > this may sound stupid, but;
> > > - I'd like to install unsupported x86/i386 smp kernel because I need 
> > > some support <snip>
> 
> > > Questions:
> > > Is there any documentation for how to install unsupported smp kernel so 
> > > that'll be able to do normal updates (like I've been updating until now 
> > > without features of unsupprted kernel) ?
> 
> I see Johnny does not say "yes" or "no". :-) Maybe a topic for an intro
> somewhere or a FAQ, although AFAICT it has not made it to FAQ status. I
> feel like this Q has enough widespread application that it may deserve
> more than a "check the archives" solution, which your post provides.

There is a readme here:

http://mirror.centos.org/centos/4/centosplus/Readme.txt

That and my instructions should be plenty good enough.  How you resolve
this issue is way to varied to try and cover it completely ... examples:

1.  You way want all the centosplus updates and not need to do anything
except exclude items from [base] and [updates] repos.

2.  You may want to use protectbase plugin and protect centosplus from
the other centos repos

3. You may be using something like yum-plugins-priorities to assign a
lower priority to centosplus than base and updates ... so you only need
to use exclude= in centosplus to remove packages that you don't want to
see ... but don't need any includepkgs= anywhere.

The bottom line is that there is documentation provided for yum in many
places, and people who want to administer a CentOS box should become
familiar with:

http://wiki.centos.org/PackageManagement/Yum

and this:

http://mirror.centos.org/centos/4/docs/html/yum/

and this:

http://wiki.centos.org/Repositories

and maybe this:

http://mirror.centos.org/centos/4/docs/html/yumex/

Then to use centosplus they should read this:

http://mirror.centos.org/centos/4/centosplus/Readme.txt

If in doubt, start on the centos-4 docs page:

http://mirror.centos.org/centos/4/docs/

or the CentOS wiki:

http://wiki.centos.org/

> 
> > > I've downloaded the kernel files (107), <snip>
> 
> > After rebooting on a new kernel, I remove the ones I don't want to save
> > by doing:
> > 
> > rpm -qa | grep kernel | sort
> 
> <OT>
> Since I have *my* habitual way of doing things (less typing) I do want
> to be sure that I'm not risking something by assuming that rpm can
> handle a "selector" just because it happened to provide good results on
> my small test. So I thought I'd ask.
> 
> "They" say "Necessity is the mother of invention". Being who/what I am,
> I assert "Laziness is the mother of invention". So ...
> 
> Why not this,
> 
>     rpm -qa kernel\*|sort  # Laziness trumping readability here, no
>                            # spaces. But that's not my main point.
> 
> instead of what you demonstrate. I tried it on my own (admittedly
> parochial) small setup and achieved identical results. I am concerned
> that my lack of breadth, such as your and other setups might have, may
> not produce identical results like mine.
> 
> I have discovered over the years that often a certain way of doing
> things are remnants of early learning (older less capable OSs, picked up
> while learning packages like bash, ...), ingrained habit, temporary
> insanity (esp. when dire results result  ;-) and have effects that may
> be unwanted: introducing increased opportunity for error in the typing,
> adding unnecessary load to the system (my speedy little red sporty car
> and Yammy YZF 750 give away my reason for this concern), taking longer
> to type the command. Uh, I *guess* n00bs learning by example would also
> be a valid concern?
> 
> Anyway, to keep from getting on my soap box, I'll mention my pet peeve
> and then quit.
> 
> # My favorite variation on this next line is cat <file_xyz
> cat file_xyz | first_command_in_pipeline rest_of_pipeline
> 
> instead of
> 
> # Here is a shorter line, with valid use of I/O redirection
> first_command_in_pipeline <file_xyz rest_of_pipeline
> 
> Again, since I have *my* habitual way of doing things (less typing) I do
> want to be sure that I'm not risking something by assuming that rpm can
> handle the "selector" just because it happened to provide good results
> on my small test.
> </OT>
> 

Should be just fine ... I just said what I did ... not that it is the
best or even a good way to do it :)

> > 
> > then
> > 
> > rpm -e kernel-xxxx kernel-devel-xxxx
> >
> > (substitute the kernels you want to get rid of)
> 
> Extending the OP's question slightly, if we have multiple <pkg X>
> installed (presuming something else might be handled as is the kernel)
> and it comes via the normal yum/repo route, should we use yum to remove
> unneeded versions? My thought is that yum should be safer since it shows
> additional information and offers a chance to change our mind.

I personally never EVER use yum to remove anything ... as it resolves
dependencies and recommends sometime tens of packages to remove.

I use yum to install  / upgrade packages, I feel much more comfortable
resolving my own dependencies when removing packages :) (that is just a
personal bias).
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