Re: 13.2 BETA2: how do debug META_MODE?

On Tue, Feb 21, 2023 at 06:44:09PM -0800, Mark Millard wrote:
! On Feb 21, 2023, at 18:10, Peter <pmc@citylink.dinoex.sub.org> wrote:
! 
! > On Tue, Feb 21, 2023 at 11:56:13AM -0800, Mark Millard wrote:
! > ! On Feb 21, 2023, at 04:55, Peter <pmc@citylink.dinoex.sub.org> wrote:
! > ! 
! > ! > ! # cd /usr/src/
! > ! > ! # env WITH_META_MODE=yes make buildworld
! > ! > ! # env WITH_META_MODE=yes make installworld
! > ! > ! # env WITH_META_MODE=yes make buildworld (again #0)
! > ! > ! ## no more rebuilds below?
! > ! > ! # env WITH_META_MODE=yes make buildworld (again #1)
! > ! > ! # env WITH_META_MODE=yes make buildworld (again #2)
! > ! > 
! > ! > But what is the difference between #0 and #1?
! > ! 
! > ! awk, cp, ln, rm, sed, and many more from
! > ! . . ./tmp/legacy/usr/sbin/have new dates
! > ! for rebuilds after installworld (that targets
! > ! the running system). Not true for #1 and #2.
! > ! 
! > ! The dates on these tools being more recent than
! > ! the files that they were involved in producing
! > ! leads to rebuilding those files. That in turn
! > ! leads to other files being rebuilt.
! > ! 
! > ! make with -dM reports the likes of:
! > ! 
! > !    file '. . ./tmp/legacy/usr/sbin/awk' is newer than the target...
! > ! 
! > ! explicitly as it goes. As I remember tmp/legacy/usr/sbin/
! > ! was always part of the path for what I found.
! > 
! > Mark, thanks a lot for the proper input at the right time!
! > 
! > This put me on the right track and I mananged to analyze and
! > understand what is actually happening.
! > 
! > It looks like my issue does resolve itself somehow, and things
! > start  to behave as expected again after four builds.
! 
! Intersting.
! 
! > ! I did not do the analysis of how (e.g.) tmp/legacy/usr/sbin/awk
! > ! ended up being newer than such a target and, so, causing a
! > ! rebuild of that target. I was going the direction: that
! > ! it is newer really is unlikely to justify the rebuild for
! > ! the target(s) in question. The other direction about how
! > ! it got to be newer is also relevant.
! > 
! > I have now analyzed some parts of it. META_MODE typically finds some
! > build-tools to rebuild, but then if the result is not different
! > from what was there before, then "install" will not copy it to the
! > bin-dir, and so the avalanche gets usually avoided.
! > 
! 
! The implication is that "install -C" is in use, quoting the
! man page:
! 
!      -C      Copy the file.  If the target file already exists and the files
!              are the same, then do not change the modification time of the
!              target.  If the target's file flags and mode need not to be
!              changed, the target's inode change time is also unchanged.
! 
!      -c      Copy the file.  This is actually the default.  The -c option is
!              only included for backwards compatibility.
! 
! -C might have more of an effect in a reproducible-build
! style build process than on a non-reproducible-build
! style one.

Yepp. "install -p" is used, see /usr/src/tools/install.sh