Re: [gentoo-user] OT ( was : Cannot boot 2.6.21-gentoo-r4)

[Albert Hopkins <marduk@gentoo.org>]

On Tue, 2007-07-17 at 14:24 -0500, Billy Wayne McCann wrote:
> My purpose for pasting this into this discussion is three-fold: to
> show
> why I said what I did, to hopefully dispel the notion that I merely
> made
> this all up, and to discuss the relevance of the pasted text itself.
> 
> I apologize for being off-topic and hope that Mick finds himself a
> working kernel config soon.  :) 

I hope he does as well.

Completely on a tangent from the OP, but I would like to argue *for* the
use of oldconfig when upgrading kernels. I read the relevant part of the
document and I'm not going to contest it, it does not seem to indicate
that "oldconfig" when upgrading kernels doesn't work, but that
"oldconfig" might somehow confuse the user into not selecting a kernel
option that they need.  OTOH if said person is using an "old config"
that worked then most, if not all, of the "needed" options are already
selected.  But what are the alternatives?  The document does not cite
any. I can think of four choices:

     1. "make menuconfig" and create a new .config from scratch.  From
        my own personal experience I know I'm *much* more likely to
        forget a needed kernel option starting from scratch than from an
        old config.
     2. Copy old .config and "make".  In this case you miss any new
        kernel options.
     3. copy old .config and "make menuconfig".  In this case you're
        much more likely to miss the *new* kernel options because they
        don't stand out from the old ones.
     4. Copy old .config and "make oldconfig".  Here you get prompted
        for any new kernel options, plus you keep all your old ones when
        feasible.

Or, if you're lucky enough to be using Gentoo, you could run genkernel.
However browsing the genkernel sources it seems to do 2, 3 or 4
depending on what options it is given. 2 seems relevant only if you want
to upgrade your kernel but not take advantage of any new features.  3 is
prone to overlooking the aforementioned features.  So that leaves 1
which is ridiculous and 4 which just about every other document found on
the net about upgrading kernels recommends, including the Greg
Kroah-Hartman's _Linux Kernel in a Nutshell_ (Greg being both a Kernel
and Gentoo developer).

I think that in general, and when used correctly, oldconfig is in fact a
very useful tool when performing kernel upgrades, but of course YMMV.


--
Albert W. Hopkins

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