Re: [gentoo-user] Kernel configuration management

[fpemud]

On 11/07/2012 05:27 AM, Matthias-Christian Ott wrote:
> I'm planning to migrate several computers to Gentoo. At the moment I'm
> running two machines with ad-hoc kernel configurations based on the
> kernel configuration from the installation CD (which was created for
> 2.6.26). In order to keep the maintenance effort for the new machines
> low, I would like to have a unified/baseline kernel configuration with
> minor adjustments for some machines.
>
> I have been thinking about this for several weeks now and came to the
> conclusion, that there are two sub-problems: Creating a universal kernel
> configuration and merging and maintaining specific configurations with
> the baseline configuration.
>
> The second problem can be solved by simple concatenation and/or
> defconfigman, kccmp and make silentoldconfig. OpenWRT does this pretty
> much the same way.
>
> Creating the baseline configuration is much harder. So far I tried make
> defconfig, the installation CD configuration and kernel-seeds.org. None
> really satisfied my requirements and often resulted in ad-hoc changes
> when I simply went through a compile and reboot cycle until everything
> worked. I had a look at policies of other GNU/Linux distributions [1,2]
> and found that I need to develop or adopt a policy for my systems (the
> Ubuntu "modular where possible" policy seems reasonable to me and
> probably makes the curent ad-hoc configuration unnecessary). I also
> thought about reusing kernel configurations from other distributions,
> but have some doubts about kernel version mismatches (i.e. the kernel
> versions of Gentoo and the other distribution differ) and about
> unintended implications of kernel options that I don't fully understand.
>
> The mailing list archives show that this topic has been partly discussed
> before (especially whether Gentoo should have a default kernel
> configuration like other distributions), so I don't want to start a
> lengthy discussion about this here. I'm more interested in what other
> people do for larger deployments/installations on heterogeneous hardware.
>
> Regards,
> Matthias-Christian
>
> [1] https://wiki.ubuntu.com/Kernel/Dev/KernelConfig
> [2] https://wiki.linaro.org/KernelConfigPolicyDraft
>
>

I'm not an enterprise user, I use gentoo at home.
I have 4 computers to maintain, 2 workstations, 1 notebook, 1 htpc

I'm encountering the same problem.
all the machine have similar but different config (including the kernel
config).
remember and sync them costs me some time.
there's some tool to COPY config between machines, but none can deal
with SIMILARITY smoothly.

for the kernel config, I'm starting to write a
policy-based-dot-config-auto-generating tool.
the policy is like:
10-no-debug: Select "n" for any debug item, but with some exceptions
10-no-deprecate: Select n for any deprecated item, with exceptions
10-no-experimental: Select n for any experimental item, with exceptions
40-no-drv-rare: Select n for some rare driver i will never use
40-no-drv-with-deep-selects: select n for some driver that has too deep
selets
50-all-net: select all the item in "Network support"
60-mod-all-drv: select m for all the drivers, like ubuntu
70-yes-key-items: select y for some key items

every policy comprises code(python?) and data.
I think every user has to write his own policy, which means writing some
script, more work than writing config file, really.

For me, I will make all my machines share the same policy code, but have
different policy data.
Sync only the policy data is easier and clearer.

For you, I think the policy structure could be "policy code" + "global
policy data" + "adjustment policy data".
And another pro is you don't need to inspect the "unified/baseline
kernel configuration" between kernel version updates.

I'm starting to write a tool syncing other cfg between my machines
either, it's another topic.

relative links (this project really just starts):
https://github.com/fpemud/fpemud-buildkernel
https://github.com/ulfalizer/Kconfiglib
http://forums.gentoo.org/viewtopic-t-933726-highlight-fpemud.html