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faeb5
n00b
Joined: 16 Jan 2022
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 Posted: Sun Jan 16, 2022 6:40 pm Post subject: Necessary and unnecessary modules for the kernel |
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Hi! First of all, big Gentoo fan! Built my very first customized kernel for a Desktop PC and it really was great experience.
However, I have a question regarding modules. How excactly do you determine what modules you should include (whether directly or as a module) in a custom kernel?
My laptop is currently running a Gentoo distribution kernel (the binary version). Before building a custom kernel I ran `lsmod` to see what modules are loaded, but there are a ton of them. Are they all necessary? Is every loaded module currently needed by some device or does the Gentoo distribution kernel load modules that are currently unsed but might be in the future?
I'm not afraid of leaving out modules, for example I don't plan on using bluetooth so I skip the bluetooh driver/module for my custom kernel, but I"m really unsure about the low-level stuff like I2C. How can you determine if this stuff is needed or not? Is it simply a matter of "if the machine runs and works then it's fine'? |
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eccerr0r
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Joined: 01 Jul 2004
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Location: almost Mile High in the USA
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| Posted: Sun Jan 16, 2022 6:49 pm Post subject: |
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Welcome to Gentoo and here starts the endless rabbit hole of install possibilities! But you knew that!
The main thing to consider is the difference between "runs" versus "runs with all the bells and whistles" like knowing your gpu temperatures and power supply voltages - you don't absolutely *need* them but it could make your life better...
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faeb5
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Joined: 16 Jan 2022
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| Posted: Sun Jan 16, 2022 7:02 pm Post subject: |
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Your point makes sense. I certainly don't need everything in there, but it's good to have thermals and indicators especially for the laptop. I'm mostly concerned about accidently leaving our power-saving features that decrease battery runtime on the laptop.
I guess the best option is to go through each and every module and read up on what it does? |
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Jaglover
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| Posted: Sun Jan 16, 2022 7:08 pm Post subject: |
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Not everything is configured as a module in default configuration. There are many options in kernel you may not need. This is not for faint of heart, but you can start with 'make allnoconfig' and start enabling options and features you need. Instead of taking a big kernel and removing options.
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eccerr0r
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Joined: 01 Jul 2004
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Location: almost Mile High in the USA
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| Posted: Sun Jan 16, 2022 7:17 pm Post subject: |
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Yes power saving features is also something that's not "world ending" (at least right away, like a missing disk, network, video, or keyboard driver) alas yes these nonfatal if missing drivers, you'll have to either know or go ahead and compile everything, they tend to automatically load when needed.
The unfortunate thing is that some of the power saving features could be controlled by i2c/smbus so leaving these things out will leave things on the table.
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Last edited by eccerr0r on Sun Jan 16, 2022 7:19 pm; edited 1 time in total |
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pietinger
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Joined: 17 Oct 2006
Posts: 4148
Location: Bavaria
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| Posted: Sun Jan 16, 2022 7:18 pm Post subject: Re: Necessary and unnecessary modules for the kernel |
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Hello faeb5,
welcome to Gentoo Forums !
| faeb5 wrote: | | Is it simply a matter of "if the machine runs and works then it's fine'? |
Mostly - with few exceptions. Yes there are some modules I have not included because I dont need it; e.g.: Intel MEI (Management Engine Interface), Intel RAPL, I2C and even LPC (Low Pin Count). Also I dont have any modules for IPv6 (I dont want/use it; data privacy reasons), initramfs and a serial and a parallel interface (I also dont have).
My system have a SSD and a HD, no extra graphics adapter (taking GPU of Intel i7), no Blutooth, no WLAN, no WebCam. Take a look to my used modules:
| Code: | # lspci -k
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers (rev 07)
Subsystem: Gigabyte Technology Co., Ltd Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
DeviceName: Onboard IGD
Subsystem: Gigabyte Technology Co., Ltd HD Graphics 530
Kernel driver in use: i915
00:08.0 System peripheral: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model
Subsystem: Gigabyte Technology Co., Ltd Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model
00:14.0 USB controller: Intel Corporation 200 Series/Z370 Chipset Family USB 3.0 xHCI Controller
Subsystem: Gigabyte Technology Co., Ltd 200 Series/Z370 Chipset Family USB 3.0 xHCI Controller
Kernel driver in use: xhci_hcd
00:16.0 Communication controller: Intel Corporation 200 Series PCH CSME HECI #1
Subsystem: Gigabyte Technology Co., Ltd 200 Series PCH CSME HECI
00:17.0 SATA controller: Intel Corporation 200 Series PCH SATA controller [AHCI mode]
Subsystem: Gigabyte Technology Co., Ltd 200 Series PCH SATA controller [AHCI mode]
Kernel driver in use: ahci
00:1b.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #17 (rev f0)
Kernel driver in use: pcieport
00:1b.2 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #19 (rev f0)
Kernel driver in use: pcieport
00:1b.4 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #21 (rev f0)
Kernel driver in use: pcieport
00:1c.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #1 (rev f0)
Kernel driver in use: pcieport
00:1c.2 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #3 (rev f0)
Kernel driver in use: pcieport
00:1c.4 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #5 (rev f0)
Kernel driver in use: pcieport
00:1d.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #9 (rev f0)
Kernel driver in use: pcieport
00:1f.0 ISA bridge: Intel Corporation 200 Series PCH LPC Controller (Z270)
Subsystem: Gigabyte Technology Co., Ltd 200 Series PCH LPC Controller (Z270)
00:1f.2 Memory controller: Intel Corporation 200 Series/Z370 Chipset Family Power Management Controller
Subsystem: Gigabyte Technology Co., Ltd 200 Series/Z370 Chipset Family Power Management Controller
00:1f.3 Audio device: Intel Corporation 200 Series PCH HD Audio
Subsystem: Gigabyte Technology Co., Ltd 200 Series PCH HD Audio
Kernel driver in use: snd_hda_intel
00:1f.4 SMBus: Intel Corporation 200 Series/Z370 Chipset Family SMBus Controller
Subsystem: Gigabyte Technology Co., Ltd 200 Series/Z370 Chipset Family SMBus Controller
Kernel driver in use: i801_smbus
04:00.0 USB controller: ASMedia Technology Inc. ASM2142 USB 3.1 Host Controller
Subsystem: Gigabyte Technology Co., Ltd ASM2142 USB 3.1 Host Controller
Kernel driver in use: xhci_hcd
05:00.0 Ethernet controller: Qualcomm Atheros Killer E2500 Gigabit Ethernet Controller (rev 10)
Subsystem: Gigabyte Technology Co., Ltd Killer E2500 Gigabit Ethernet Controller
Kernel driver in use: alx |
But there are also some settings which affects performance and security (I prioritize security over performance). Here you have decide by yourself what you want. Maybe some links will help you:
- https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
- https://wiki.gentoo.org/wiki/Power_management/Guide (for a desktop I recommend: "performance governor")
- https://wiki.gentoo.org/wiki/System_time (I let my kernel sync the system clock)
I have in my kernel also all needed modules for a firewall (netfilter modules), AppAprmor, IMA and encryption (dmcrypt).
Hint: If something is missing in your kernel you will notice it at once (because something doesnt work); if you have modules in your kernel you will never use, you will notice it never => Configure as less as possible for the beginning ! |
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pietinger
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Jaglover
Watchman
Joined: 29 May 2005
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Location: Saint Amant, Acadiana
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| Posted: Sun Jan 16, 2022 7:58 pm Post subject: |
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| pietinger wrote: | | Jaglover wrote: | | [...] but you can start with 'make allnoconfig' [...] |
I dont recommend this hard way ... |
faeb5,
you make your own choices, don't listen to pietinger. He has a habit to evaluate everything from his own point of view without recognizing people are different. What is hard for him may be fun for someone else. In particular a moderator should not push his opinions.
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54234
Location: 56N 3W
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| Posted: Sun Jan 16, 2022 8:42 pm Post subject: |
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faeb5,
The method that I like is still valid but the detail has changed since I posted that.
The kernel has got a lot bigger, so you need more coffee.
pappy_mcfae expanded that in his kernel seeds site.
Its the same method with a worked example based on what is now an old kernel.
-- edit --
The default kernel configuration is not useful to anyone, so if you start with all on, all off, or something in between, you still have to read all the help and make up you own mind if you need an option or not.
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NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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pietinger
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faeb5
n00b
Joined: 16 Jan 2022
Posts: 3
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| Posted: Mon Jan 17, 2022 5:25 am Post subject: |
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Thanks for the infos! I sure have a lot of reading to do! Looking forward to getting more basic knowledge about the different kernel stuff.
I'll guess that for my laptop I will try and include the stuff I think I'll definitely need on a daily or weekly basis and if I find out that I haven't used feature X for some time I'll think about kicking it out. My desktop kernel is a monolithic one but I'm beginning to like the idea of modules because it keeps the kernel lean without sacrificing the ability to load features when you need them.
Btw, I'm actually glad that I started to using Gentoo in 2021 because re-compiling kernels with 8 or 12 core CPUs is way more fun that it would have been may years back.  |
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eccerr0r
Watchman
Joined: 01 Jul 2004
Posts: 9679
Location: almost Mile High in the USA
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| Posted: Mon Jan 17, 2022 8:16 am Post subject: |
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| faeb5 wrote: | | Btw, I'm actually glad that I started to using Gentoo in 2021 because re-compiling kernels with 8 or 12 core CPUs is way more fun that it would have been may years back. :D |
I don't think it really matters. My fastest kernel compile was 2 minutes, and that was back when I was using my dual celeron 450 (unfortunately this was prior to when I got into Gentoo).
I have not had a faster compile since then... Gcc just gets fatter and fatter, kernel gets fatter and fatter, computer gets faster but not that much as gcc/kernel have gotten fatter and fatter.
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Leonardo.b
Apprentice
Joined: 10 Oct 2020
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Kernel & Hardware
