svn commit: r350550 - head/share/mk

[Rodney W. Grimes]

> On 07/08/2019 15:12, Rodney W. Grimes wrote:
> >> On 07/08/2019 11:00, John Baldwin 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.
> >> +1 keeping metadata in head.
> > I am conflicted on this one, and I think there is a reasonable argument
> > on both sides, but from what I have read here this appears to be mostly
> > the kernel that is at issue, loss of the meta data from newvers.sh in
> > the kernel is infact a PITA, even on stable or production release
> > systems.
> >
> > I propose a compromise, add 2 knobs:
> > WITHOUT_REPRODUCIBLE_KERNEL	(aka get your metadata in uname)
> > WITH_REPRODUCIBLE_USERLAND	(aka reproducible userland)
> >
> > WITH{,OUT}_REPRODUCIBLE_BUILD overrides both, for backwards compat,
> > and neither should be defined by default.
> Too complex IMHO. Either the system is reproducible or it isn't.
> > Somehow set WITH_REPRODUCIBLE_KERNEL for builds of GENERIC
> > for releases/snapshots, but do not ship the system with it
> > set (I can here a growl from Glen on this)  Thus we build
> > a reproducible kernel and ship it with the system but if
> > the user builds a kernel it gets meta data to indicate it
> > is no longer a stock kernel.
> > FYI, upon finding I could not figure out what kernel I was running
> > after installing 12.0 release I turnd off REPRODUCIBLE on my kernel
> > build VM for 12.0.  I do leave it on if I am building userland.
> >
> > Thoughts?
> 
> Among other things, reproducible builds implies that pkg upgrades are 
Do you mean freebsd-update?

> smaller. I see it makes sense to make releases, and in fact -stable, 
> completely reproducible. For -current I am fine with it not being 
> reproducible,
> 
> All just IMHO.

Let me try to add a case for it on ^head, weekly snapshots
are built, if ^head was running reproducible it would be
possible to diff these snapshots in a meaniful way.

It would also mean one could get pretty creative with ZFS,
zfs-snapshots and the built snapshots to actually have on
line almost all binary versions of ^head in a fairly compact
form.

> Pedro.
-- 
Rod Grimes                                                 rgrimes at freebsd.org