[RFE] Enable makedumpfile invocation from initramfs

[Pedro Principeza]

[Request]
To be able to call makedumpfile at the from the initramfs, instead of doing so after rootfs is active/mounted.

[Justification]
Systems with too much memory will demand higher amounts of memory for the crashkernel parameter, as well as having less systemd units up and running before makedumpfile kicks in. The idea is to use as little memory as possible in the kernel dump generation.

[Workaround]
Tailoring the postinst.d/kdump-tools hooks can have makedumpfile be called earler. Although feasible, that's too much of a "hack", and this could ideally be embedded in kdump-tools as an option.

[Regressions]
TBE.

[Guilherme G. Piccoli (gpiccoli)]

Thanks Pedro for the LP! Related Debian MR: https://salsa.debian.org/debian/makedumpfile/-/merge_requests/1

The approach taken in the above Debian MR is pretty complex and involve more than just kdump from initrd.
The idea to implement such feature in a simple and safe way would be to have it as an optional configuration and when that feature is set, an initramfs hook adds the necessary tooling to the kdump initrd; then a script could run and collect the kdump from init-bottom (or local/fs-bottom).

Cascardo, do you agree with that?
Cheers,

Guilherme