Why is the kernel so big?

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Why is the kernel so big?

Postby nbd » Wed Jul 20, 2016 1:34 am

Greetings!

The 'top' command on ArchArm (lxde DE and almost no user daemons) shows 185 running processes which is way more than on Arch on my desktop with XFCE. Also the kernel image size is about 6 Mb on ArchArm, whereas on Arch it's 4.7 Mb. I understand that I probably need to compile a custom kernel with needed modules only, but why the situation is different with "normal" Arch? Is the kernel image used in ArchArm is compiled somewhere upstream, and is intended to work out of the box in all cases without any configuring and initrd?


Thanks.
Albert.
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Re: Why is the kernel so big?

Postby moonman » Wed Jul 20, 2016 1:58 am

Yup, depending on the kernel (device) modules required for bringing the device up are compiled in so that there is no requirement for initramfs. In the end it doesn't matter since if they were to be compiled separately they would have to be loaded either way.
You did not mention your device.
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Re: Why is the kernel so big?

Postby nbd » Wed Jul 20, 2016 4:33 am

The device is Raspberry Pi 2. E.g. I see many processes such as 'jfsCommit' or 'xfsalloc" - do they relate to xfs and jfs filesystems? I have neither installed. Another example two early loaded 'pencrypt' processes - are they for encrypted fs's? I don't have encrypted fs as well. It's my understanding, that were they included only on initrd, they would be unloaded when the memory where initrd resides is freed in the end of boot process.
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Re: Why is the kernel so big?

Postby moonman » Wed Jul 20, 2016 5:08 am

Because xfs support is built in. Well what do you lose? 1-2 mBytes... maybe?
Pogoplug V4 | GoFlex Home | Raspberry Pi 4 4GB | CuBox-i4 Pro | ClearFog | BeagleBone Black | Odroid U2 | Odroid C1 | Odroid XU4
-----------------------------------------------------------------------------------------------------------------------
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