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Date:      Fri, 13 Dec 2024 16:42:13 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        Ed Maste <emaste@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   RE: Switching release media dist sets to .tzst (tar + zstd)?
Message-ID:  <E7CF486A-81BE-4B1C-A1E4-6B820F454259@yahoo.com>
References:  <E7CF486A-81BE-4B1C-A1E4-6B820F454259.ref@yahoo.com>

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Ed Maste <emaste_at_freebsd.org> wrote on
Date: Fri, 13 Dec 2024 21:15:45 UTC "

> I have been reviewing parts of the release artifact build process,
> including ISO and memstick images, and came across the distribution
> sets (e.g., base.txz, src.txz) used by the installer to populate new
> file systems. I=E2=80=99d like to discuss switching these to .tzst =
(tar +
> zstd) compression.

My notes are mostly not about the specific compression format --but
are about the dist-sets potentially going away.

I tend to use https://artifact.ci.freebsd.org/snapshot/*/*/*/*/*.txz
for crude bisecting without needing to do builds. For example, grabbing
something like:

=
https://artifact.ci.freebsd.org/snapshot/main/926905796749750da6464b97ec4f=
8eec0882cc0e/arm64/aarch64/kernel.txz
=
https://artifact.ci.freebsd.org/snapshot/main/926905796749750da6464b97ec4f=
8eec0882cc0e/arm64/aarch64/kernel-dbg.txz

to see compare/contrast behavior with other builds. This also avoids
questions about if my builds create any problems vs. official builds.

> While I haven=E2=80=99t yet conducted detailed benchmarks comparing =
zstd and
> xz specifically for this use case, here are some initial
> considerations:
>=20
> Pros of zstd:
> - Faster compression and decompression speeds.
> - Aligns with the compression method used for FreeBSD packages.
>=20
> Cons of zstd:
> - Somewhat larger compressed file sizes.
> - Requires updates to tools that interact with distribution sets.
> - May have limited availability on some other operating systems (?).
>=20
> I have a review open to demonstrate the extent of the change in the
> build system & installer: https://reviews.freebsd.org/D48042
>=20
> It might be that this is not worth pursuing, as dist sets will most
> likely go away with the migration to pkgbase,

I tend to use https://artifact.ci.freebsd.org/snapshot/*/*/*/*/*.txz
for crude bisecting without needing to do builds.

Are you saying that such will no longer be a possibility? (This is
not a which-compression-style question.)

I've also used the likes of the below with kgdb to look at reported
backtraces from problems that have been reported --for versions of
FreeBSD that I do not have a boot environment for. (Not wanting to
do a normal install on other media and to boot/configure it --just
to look around.)

=
http://ftp3.freebsd.org/pub/FreeBSD/releases/amd64/14.2-RELEASE/kernel.txz=

=
http://ftp3.freebsd.org/pub/FreeBSD/releases/amd64/14.2-RELEASE/kernel-dbg=
.txz
http://ftp3.freebsd.org/pub/FreeBSD/releases/amd64/14.2-RELEASE/src.txz

(But there is no equivalent for patch revisions of *.*-RELEASE 's .)

=
http://ftp3.freebsd.org/pub/FreeBSD/snapshots/arm64/13.4-STABLE/kernel.txz=

=
http://ftp3.freebsd.org/pub/FreeBSD/snapshots/arm64/13.4-STABLE/kernel-dbg=
.txz
http://ftp3.freebsd.org/pub/FreeBSD/snapshots/arm64/13.4-STABLE/src.txz

Similar question for those: no longer to be possible?


> but I would like to
> discuss and make an explicit decision. We can separately consider
> compression on the release media images themselves.
>=20
> Feedback Requested:
>=20
> Is there support for this idea? Are there objections to pursuing this?
> Are there other factors I should consider, especially compatibility =
concerns?

=3D=3D=3D
Mark Millard
marklmi at yahoo.com




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