[ISSUE] RFC: move kernels out of /boot

[ISSUE] RFC: move kernels out of /boot

[Duncaen]

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New issue by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/issues/48024

Description:
Some distributions have started to move the kernels out of the boot directory by default and let the install hooks etc handle copying them over.

The kernel hooks would then copy the kernels into `/boot`, users could then change the hooks to i.e. allow to create unified kernel image (UKI) executable without the extra duplication between the UKI file and the package dropped kernel binary.

Seems like the "standard" location for kernel files would be `/usr/lib/modules/${VERSION}/vmlinuz`.

Advantages:
 - kernels can be copied to /boot and modified for i.e. signing.
 - kernels don't have to be copied to /boot for UKIs.
 - kernel.d post install moves kernels after the initramfs hook, the stupid grub mkconfig wouldn't put up kernels for which initramfs generation failed. (https://github.com/void-linux/void-packages/issues/46006)
 - Maybe good for raspberrypi kernels too, let install hooks move them to the weird kernel8.img names? 

Re: RFC: move kernels out of /boot

[dkwo]

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New comment by dkwo on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1873903895

Comment:
Good idea. This is also useful on apple silicon, where you concatenate a payload for m1n1.

Re: RFC: move kernels out of /boot

[mbsmith]

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New comment by mbsmith on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1883343182

Comment:
Well that goes against the [https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s05.html](boot) section of FHS 3.0.  However if we're not trying to comply to that I don't see an issue.  I double checked to see if SUS/POSIX has any issues with it and it appears it doesn't.  I'm all for it.

Re: RFC: move kernels out of /boot

[classabbyamp]

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New comment by classabbyamp on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1883347099

Comment:
no it doesn't. this is only for how they are packaged:

> The kernel hooks would then copy the kernels into /boot, users could then change the hooks to i.e. allow to create unified kernel image (UKI) executable without the extra duplication between the UKI file and the package dropped kernel binary.

Re: RFC: move kernels out of /boot

[classabbyamp]

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New comment by classabbyamp on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1883347099

Comment:
no it doesn't. this is only for how they are packaged:

> The kernel hooks would then copy the kernels into /boot, users could then change the hooks to i.e. allow to create unified kernel image (UKI) executable without the extra duplication between the UKI file and the package dropped kernel binary.

> Thus /boot stores data that is used before the kernel begins executing user-mode programs. This may include saved master boot sectors and sector map files.

Re: RFC: move kernels out of /boot

[classabbyamp]

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New comment by classabbyamp on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1883347099

Comment:
no it doesn't. this is only for how they are packaged:

> The kernel hooks would then copy the kernels into /boot, users could then change the hooks to i.e. allow to create unified kernel image (UKI) executable without the extra duplication between the UKI file and the package dropped kernel binary.

Re: RFC: move kernels out of /boot

[mbsmith]

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New comment by mbsmith on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1883343182

Comment:
I'm all for it.

Re: RFC: move kernels out of /boot

[Jipok]

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New comment by Jipok on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1898669655

Comment:
I'm glad that at least someone is thinking about solving an important problem(https://github.com/void-linux/void-packages/issues/46006). But getting UKI involved annoying me. Are the goals of this decision even that useful to people? It seemed to me that it was created only to oppress people and the benefits offered are so minimalistic that the quote “Those who are ready to exchange freedom for security are worthy of neither freedom nor security” comes to mind.
UKI gives "Providing a fully verified boot process", that is, bad corporations can prohibit the user from changing the kernel (and, accordingly, the system) as is the case now on Android. And other delights in the form of the inability to boot if you live in the “wrong” country. And also contributes to the implementation of DRM. And vendorlock. LinuxD damn.

Re: RFC: move kernels out of /boot

[Johnnynator]

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New comment by Jipok on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1898669655

Comment:
I'm glad that at least someone is thinking about solving an important problem(https://github.com/void-linux/void-packages/issues/46006). But getting UKI involved annoying me. Are the goals of this decision even that useful to people? It seemed to me that it was created only to oppress people and the benefits offered are so minimalistic that the quote “Those who are ready to exchange freedom for security are worthy of neither freedom nor security” comes to mind.
UKI gives "Providing a fully verified boot process", that is, bad corporations can prohibit the user from changing the kernel (and, accordingly, the system) as is the case now on Android. And other delights in the form of the inability to boot if you live in the “wrong” country. And also contributes to the implementation of DRM. And vendorlock. LinuxD damn.

Re: RFC: move kernels out of /boot

[CtrlC-Root]

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New comment by CtrlC-Root on void-packages repository

https://github.com/void-linux/void-packages/issues/48024#issuecomment-1938812385

Comment:
I think this would be valuable especially if there is an easy way to make local changes to or extend the hooks in order to implement custom behavior.

Background context:

I have been attempting to use Void Linux on embedded systems with fairly limited disk space. These systems typically have a separate `/boot` partition and one challenge I've run into has been sizing it appropriately; if it's too large you end up wasting precious space but if it's too small you risk breaking system updates (or requiring manual intervention). This is made more complicated by the fact that it's difficult to predict the size of generated initramfs images ahead of time (since they occasionally increase). Right now I have solved this with a script that wraps `xbps-install` and makes sure you end up with the right things in `/boot` (it's not 100% full and it has files necessary to boot) after it's done running. I have seen the warnings printed during `xbps-install` that mention the system may not be bootable due to low disk space in `/boot` but (1) assuming I've sized it appropriately it should be mostly full all of the time and (2) I know what the right thing to do is in my situation and I'd like to have it done automatically so I can run `xbps-install` unattended.