Supporting LZ4 as initramfs compressor

[Dimitri John Ledkov]

On Wed, 5 Jun 2019 at 19:59, Steve Langasek <steve.langasek at ubuntu.com> wrote:
>
> Hi Dimitri,
>
> One point here:
>
> On Wed, Jun 05, 2019 at 01:15:48PM +0100, Dimitri John Ledkov wrote:
> > - lz4 size weight over gzip is marginal (14%) but imho worth the
> > improved boot time & initrd creation time
>
> A 14% increase in initramfs size is NOT marginal.  Since there are (and will
> always be) various scenarios which require a separate /boot partition, we
> have over several cycles been contending with how to ensure a clean upgrade
> as kernel+initramfs sizes increase over time and push up against the space
> limits of the boot partitions that have historically been created.
>
> If you are making a change that increases the size of initramfses by 14%
> across the board, you must also:
>
>  - update the ubuntu-release-upgrader code to take this into account so
>    users don't run out of space in the middle of the upgrade
>    - possibly in a way that is smart enough to know if a user is already
>      configuring initramfs-tools to use a non-default compressor, to avoid
>      false-positives
>  - check that the minimum size requirements for /boot that are encoded in
>    the installers are still adequate, or if they need updating (and if they
>    need updating, update this back to 18.04)
>  - document this issue in the release notes

agree.

-- 
Regards,

Dimitri.