svn commit: r350550 - head/share/mk

Warner Losh imp at bsdimp.com
Wed Aug 7 16:24:28 UTC 2019


On Wed, Aug 7, 2019 at 10:01 AM John Baldwin <jhb at freebsd.org> wrote:

> On 8/6/19 9:56 AM, Glen Barber wrote:
> > On Sat, Aug 03, 2019 at 01:06:18AM +0000, John Baldwin wrote:
> >> Author: jhb
> >> Date: Sat Aug  3 01:06:17 2019
> >> New Revision: 350550
> >> URL: https://svnweb.freebsd.org/changeset/base/350550
> >>
> >> Log:
> >>   Flip REPRODUCIBLE_BUILD back to off by default in head.
> >>
> >>   Having the full uname output can be useful on head even with
> >>   unmodified trees or trees that newvers.sh fails to recognize as
> >>   modified.
> >>
> >>   Reviewed by:       emaste
> >>   Differential Revision:     https://reviews.freebsd.org/D20895
> >>
> >
> > I would like to request this commit be reverted.  While the original
> > commit message to enable this knob stated the commit would be reverted
> > after stable/12 branched, I have seen no public complaints about
> > enabling REPRODUCIBLE_BUILD by default (and quite honestly, do not see
> > the benefit of disabling it by default -- why wouldn't we want
> > reproducibility?).
> >
> > To me, this feels like a step backwards, with no tangible benefit.
> > Note, newvers.sh does properly detect a modified tree if it can find
> > the VCS metadata directory (i.e., .git, .svn) -- I know this because
> > I personally helped with it.
> >
> > In my opinion, those that want the non-reproducible metadata included in
> > output from 'uname -a' should set WITHOUT_REPRODUCIBLE_BUILDS in their
> > src.conf.  Turning off a sane default for the benefit of what I suspect
> > is likely a short list of use cases feels like a step in the wrong
> > direction.
>
> My arguments for flipping this in head (and head only) are that the data
> provided in uname -a when this is disabled is useful for development, and
> that in head we do tailor settings towards development (e.g. GENERIC in
> head vs GENERIC in stable).
>
> The logic to handle modified trees has an inherent assumption that I think
> is false, at least for my workflow and I suspect many others.  I do builds
> and tests of kernels on separate machines (VMs or bare metal) from where I
> use VCS to manage sources so that a kernel crash doesn't toast my source
> tree.  The trees are then shared to the build/test machines via NFS.  As
> a result, the build/test machines are not always able to detect that the
> tree is modified either because a subset of the checkout is exported via
> NFS, or the VCS tool isn't installed on the build/test machines because
> they are generally barebones systems with only a base installed.  This
> does mean that flipping the knob off doesn't provide all of the same info,
> but it does provide the path, and the path matters because 'kgdb -n last'
> uses it, and because if you use separate directories for separate projects
> (e.g. git worktrees), then the path tells you which test kernel you booted.
> (It is not uncommon for me to have several test projects in flight on a
> single test machine for different branches.)
>
> In the original discussion on arch, we collectively recognized that
> developer builds vs release builds were different and needed different
> defaults.  The compromise reached at that time was to depend on the VCS
> to detect developer builds to choose the policy.  What I have found is that
> in practice for at least my workflow that doesn't actually work.  I posit
> that the majority of kernels built from head are developer builds, not
> releases, and that the default should cater to that.  You could also always
> patch release.sh to set WITH_REPRODUCIBLE_BUILD in the environment which I
> think would give a more accurate sense of when builds are releases or not.
>
> However, I will yield to whatever the consensus is.
>

I'm with John here: the dirty tree stuff is too fragile for the diversity
of development environments that are typical on -current, but not typical
on -stable. We should not revert this.

Warner


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