[gentoo-user] Fwd: Creating a custom kernel from a -bin kernel

[gentoo-user] Fwd: Creating a custom kernel from a -bin kernel

[Andrew Lowe]

For some reason this didn't go through yesterday so, once again......


-------- Forwarded Message --------
Subject: Creating a custom kernel from a -bin kernel
Date: Sat, 5 Oct 2024 18:55:50 +0800
From: Andrew Lowe <agl@wht.com.au>
Reply-To: agl@wht.com.au
Organization: Wombat High Tech
To: gentoo-user@lists.gentoo.org

Dear all,
	I'm in the process of building a new machine. To get things up and 
running I've decided to go with the gentoo-sources-bin kernel initially, 
then once I get things basically working as I want I will go back to 
building my kernels manually.

	I've now reached that point, "hand rolling" the kernel, but it is a 
pain, the first time round, getting things right.

	I have a recollection of reading somewhere online mention of a script 
that will take the .config file from the "-bin" kernel and then 
modprobe, I think, each listed module in turn to see if it is actually 
being used and subsequently writing a new .config file that now only 
contains the modules/options that the specific machine needs.

	Is this a mythical script that I have dreamt up after a long day and 
too much chocolate or does it actually exist and does anyone have a link.

	Thanks for any thoughts,

		Andrew

Re: [gentoo-user] Fwd: Creating a custom kernel from a -bin kernel

[Michael]

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Hi Andrew,

On Sunday 6 October 2024 15:16:46 BST Andrew Lowe wrote:
> For some reason this didn't go through yesterday so, once again......
> 
> 
> -------- Forwarded Message --------
> Subject: Creating a custom kernel from a -bin kernel
> Date: Sat, 5 Oct 2024 18:55:50 +0800
> From: Andrew Lowe <agl@wht.com.au>
> Reply-To: agl@wht.com.au
> Organization: Wombat High Tech
> To: gentoo-user@lists.gentoo.org
> 
> Dear all,
> 	I'm in the process of building a new machine. To get things up and
> running I've decided to go with the gentoo-sources-bin kernel initially,
> then once I get things basically working as I want I will go back to
> building my kernels manually.
> 
> 	I've now reached that point, "hand rolling" the kernel, but it is a
> pain, the first time round, getting things right.
> 
> 	I have a recollection of reading somewhere online mention of a 
script
> that will take the .config file from the "-bin" kernel and then
> modprobe, I think, each listed module in turn to see if it is actually
> being used and subsequently writing a new .config file that now only
> contains the modules/options that the specific machine needs.
> 
> 	Is this a mythical script that I have dreamt up after a long day and
> too much chocolate or does it actually exist and does anyone have a link.
> 
> 	Thanks for any thoughts,
> 
> 		Andrew

Have a look at this page:

https://wiki.gentoo.org/wiki/Kernel/Configuration

In particular, take notice of 'make localmodconfig'.

Once you have a customised kernel as you like it and it boots successfully, 
you can copy your good /usr/src/linux/.config to any subsequently emerged new 
gentoo-source kernel trees and run 'make oldconfig' thereafter, to only have 
to deal with new kernel options.

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[gentoo-user] Re: Creating a custom kernel from a -bin kernel

[Peter Böhm]

> Have a look at this page:
>
> https://wiki.gentoo.org/wiki/Kernel/Configuration

or take the hard way and do it yourself:

https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/
Manual_kernel_configuration

Re: [gentoo-user] Fwd: Creating a custom kernel from a -bin kernel

[Eli Schwartz]

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On 10/9/24 6:08 PM, Michael wrote:
>> 	I have a recollection of reading somewhere online mention of a 
> script
>> that will take the .config file from the "-bin" kernel and then
>> modprobe, I think, each listed module in turn to see if it is actually
>> being used and subsequently writing a new .config file that now only
>> contains the modules/options that the specific machine needs.
>>
>> 	Is this a mythical script that I have dreamt up after a long day and
>> too much chocolate or does it actually exist and does anyone have a link.
>>
>> 	Thanks for any thoughts,
>>
>> 		Andrew
> 
> Have a look at this page:
> 
> https://wiki.gentoo.org/wiki/Kernel/Configuration
> 
> In particular, take notice of 'make localmodconfig'.
> 
> Once you have a customised kernel as you like it and it boots successfully, 
> you can copy your good /usr/src/linux/.config to any subsequently emerged new 
> gentoo-source kernel trees and run 'make oldconfig' thereafter, to only have 
> to deal with new kernel options.


See also https://wiki.gentoo.org/wiki/Modprobed-db

"make localmodconfig" will only handle what your current system state is
using right at that second -- modprobed-db maintains a database over
time of the modules that "make localmodconfig" would see, which means
you can run the -bin kernel for a bit under your usual workloads and
then activate "make localmodconfig" via that database without worrying
about "an important module I often use was not loaded today specifically
because I didn't run the program which needs it today. Now the newly
built kernel doesn't have that module at all, oops".


-- 
Eli Schwartz

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