Wednesday, 5 June 2019

Re: Supporting LZ4 as initramfs compressor

On Wed, 5 Jun 2019 at 19:59, Steve Langasek <> 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




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