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0 pointsTwirrim6y ago0 comments

dracut on RHEL7+ builds the initramfs in "host_only" mode, which attempts to strip it down to just the kernel modules you need for boot time.

Which is also somewhat annoying because it completely trashes portability, which can be really irritating in cloud environments.

Ubuntu has similar capability (and I'm guessing Debian upstream?), but you have to specifically enable it, by default it ships the full modules set in the initramfs.

I would imagine most places outside of embedded world and maybe microvms, this stuff isn't that valuable.

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dvdkhlng6y ago· 2 in thread

Slight correction: by default Debian/Ubuntu put all modules potentially required for initial boot into the initramfs. That's still a very small percentage of all modules. I.e. you only need those modules that will get you so far into the boot process that you have access to the root partition with all the remaining modules.

E.g. if you want to do network-boot over wifi, you'll have to add a initramfs-hook script to add the wifi modules for your hardware into the initramfs [1]. They are not included by default.

[1] http://www.marcfargas.com/posts/enable-wireless-debian-initr...

TwirrimOP6y ago

You're right, I misinterpreted what "most" meant in the mkinitramfs config. Interesting. I've not seen any difficulties with porting Ubuntu between different hardware configurations, so it seems to include a reasonable amount of them.

Every now and then I'm tempted to try "dep" instead of "most", but then I realise there just isn't enough benefit!

ndesaulniers6y ago

Is there a way to specify when running mkinitramfs whether kernel modules are stored there or not?

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