Most of %%FreeBSD%% builds "reproducibly" (aka. with two builds producing identical binaries) but there are a few deviations from this.  It would be great if these could be eliminated.

====== Reproducible Builds ======
The [[https://reproducible-builds.org/|Reproducible Builds]] website has more information on the Reproducible Builds initiative, including the [[https://reproducible-builds.org/docs/definition/|Reproducible Builds Definition]].

====== Known problem files in the base system ======

===== /boot/{loader, pxeboot, userboot.so, zfsloader} =====

Contain build time/date. Option to disable added in [[https://svnweb.freebsd.org/base?view=revision&revision=310268|r310268]].

===== /boot/kernel/kernel =====

Contains time/date, user, and host. See https://reviews.freebsd.org/D4347.
Beginning of fix in [[https://svnweb.freebsd.org/base?view=revision&revision=310112|r310112]].
Option to disable added in [[https://svnweb.freebsd.org/base?view=revision&revision=310128|r310128]].

===== Kernel modules with full paths (in non-debug sections) =====

Reported by the Debian GNU/kFreeBSD folks. Specifying ''%%.PATH: $(.CURDIR)/foo/bar%%'' in a Makefile expands ''%%${.CURDIR}%%'' to an absolute path. Debian used relative paths instead: ''%%.PATH foo/bar%%''.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=757629

From the Debian report,

<code>
* modules are built with -DKLD_MODULE
* KLD_MODULE causes LOCK_DEBUG to be defined (sys/lock.h)
* LOCK_DEBUG causes mtx_assert() to use __FILE__ in debug messages (sys/mutex.h)
</code>

====== Triage required ======

The build option survey (from phk@, recently resurrected by bz@) demonstrated possible non-reproducibility in a number of files unrelated to the option being tested - for example:

<code>
usr/lib/debug/boot/kernel/aacraid.ko.debug file size=429288
usr/lib/debug/boot/kernel/aacraid.ko.debug file size=429280
usr/lib/debug/boot/kernel/acpi_asus.ko.debug file size=72032
usr/lib/debug/boot/kernel/acpi_asus.ko.debug file size=72024
</code>

Failures appear to be a variety of different kernel module .debug files.

===== Different version of yacc used in build =====
Perhaps a build race?

<code>
--- obj-repro.a/sparc64.sparc64/scratch/tmp/emaste/freebsd/tmp/scratch/tmp/emaste/freebsd/usr.sbin/config/y.tab.c       2016-12-20 14:13:03.000000000 -0500
+++ obj-repro.b/sparc64.sparc64/scratch/tmp/emaste/freebsd/tmp/scratch/tmp/emaste/freebsd/usr.sbin/config/y.tab.c       2016-12-21 07:56:10.000000000 -0500
@@ -5,7 +5,7 @@
 #define YYBYACC 1
 #define YYMAJOR 1
 #define YYMINOR 9
-#define YYPATCH 20161202
+#define YYPATCH 20160324
 
 #define YYEMPTY        (-1)
 #define yyclearin      (yychar = YYEMPTY)
...
</code>

===== Resolved issues =====

^ File ^ Issue ^ Fix Revision ^
| /usr/include/osreldate.h | copyright year; now derived from src/COPYRIGHT (Previously the build year was placed in the Copyright statement.  This isn't even valid since the passage of time doesn't create new copyrightable work.) | [[https://svnweb.freebsd.org/base?view=revision&revision=274458|r274458]] |
| /usr/sbin/amd | Build host and user (still contains the build OS name and version) | [[https://svnweb.freebsd.org/base?view=revision&revision=264374|r264374]] |
| /usr/sbin/bhyve | build date/time | [[https://svnweb.freebsd.org/base?view=revision&revision=267949|r267949]] |
| /etc/mail/*.cf | contains the user and host names from the build | [[https://svnweb.freebsd.org/base?view=revision&revision=277787|r277787]] |
| /usr/bin/svnlite | weird things happening here, even after time stamps were removed in [[https://svnweb.freebsd.org/base?view=revision&revision=257129|r257129]]. | Fixed in an unknown revision. |
| /usr/share/doc/psd/13.rcs/paper.ascii.gz | contains the build date | [[https://svnweb.freebsd.org/base?view=revision&revision=295702|r295702]] |
| /var/db/mergemaster.mtree | contains user and host names, and the build time | [[https://svnweb.freebsd.org/base?view=revision&revision=301584|r301584]] |
| /usr/share/man/man1/eqn.1.gz etc. | groff man pages, contain source checkout date | [[https://svnweb.freebsd.org/base?view=revision&revision=306740|r306740]] |
| /usr/share/man/mandoc.db, /usr/share/openssl/man/mandoc.db | ordering determined by inode number used as hash key | [[https://svnweb.freebsd.org/base?view=revision&revision=307003|r307003]] |
| tests/sys/geom/class/uzip | generated geom_uzip filesystem images are now in svn | [[https://svnweb.freebsd.org/base?view=revision&revision=307625|r307625]] |