For many years, I have reliably used read-only partitions for /usr and /usr/local. -current sysmerge breaks that assumption.
i7v64:OpenBSD/sysmerge 980>CMD="env PAGER=cat sysmerge -b -s ${ETC_TGZ} -x ${XETC_TGZ}" i7v64:OpenBSD/sysmerge 981>sudo $CMD ===> Fetching file:///nas2/public/OpenBSD/snapshots/amd64/etc56.tgz ===> Fetching file:///nas2/public/OpenBSD/snapshots/amd64/SHA256.sig ===> Verifying etc56.tgz against /etc/signify/openbsd-56-base.pub ===> Fetching file:///nas2/public/OpenBSD/snapshots/amd64/xetc56.tgz ===> Verifying xetc56.tgz against /etc/signify/openbsd-56-base.pub ===> Populating temporary root under /var/tmp/sysmerge.GhoorXuSHR/temproot mv: rename /var/tmp/sysmerge.GhoorXuSHR/etcsum to //usr/share/sysmerge/etcsum: Read-only file system mv: rename /var/tmp/sysmerge.GhoorXuSHR/xetcsum to //usr/share/sysmerge/xetcsum: Read-only file system ===> Starting comparison ===> ./etc/changelist will remain for your consideration ===> ./etc/rc.conf will remain for your consideration ===> ./etc/ssh/sshd_config will remain for your consideration ===> ./etc/systrace/usr_sbin_lpd will remain for your consideration ===> ./etc/systrace/usr_sbin_named will remain for your consideration ===> ./etc/ttys will remain for your consideration ===> ./etc/X11/xdm/xdm-config will remain for your consideration ===> ./etc/mail/aliases will remain for your consideration sha256: ///usr/share/sysmerge/examplessum: Read-only file system **** ERROR: failed to create examplessum checksum file Here's a fix for current and the FAQ: retrieving revision 1.526 diff -u -p -u -p -r1.526 current.html --- current.html 14 Jul 2014 05:48:51 -0000 1.526 +++ current.html 18 Jul 2014 16:14:07 -0000 @@ -62,6 +62,7 @@ <li><a href="#20140710">2014/07/10 - ifconfig(8) ABI break</a> <li><a href="#20140711">2014/07/11 - IPv6 autoconf changes</a> <li><a href="#20140713">2014/07/13 - Addition of sendsyslog(2) system call</a> +<li><a href="#20140716">2014/07/16 - sysmerge requires writeable /usr partition</a> </ul> @@ -628,6 +629,11 @@ sendsyslog(2) system call introduced aro <p> A kernel containing the system call is required perhaps even for getting single user; so use of upgrades is recommended. + +<a name="20140716"></a> +<h3>2014/07/16 - sysmerge requires writeable /usr partition</h3> +The /usr filesystem must be writeable. A read-only partition will +result in failures reported by sysmerge. <hr> <br> Index: faq4.html =================================================================== RCS file: /pub2/cvsroot/OpenBSD/www/faq/faq4.html,v retrieving revision 1.339 diff -u -p -u -p -r1.339 faq4.html --- faq4.html 15 Jul 2014 00:24:32 -0000 1.339 +++ faq4.html 18 Jul 2014 15:58:50 -0000 @@ -2331,9 +2331,7 @@ Some of the things that end up here (and This is where most of OpenBSD resides. Program binaries, libraries, documentation, manual pages, etc. are all located in the <tt>/usr</tt> directory. -The files in this mount point are relatively unchanging -- in many -cases, you could easily mount the <tt>/usr</tt> partition read-only with -no other system changes until your next upgrade or update. +The files in this mount point are relatively unchanging. <li><b>/usr/X11R6:</b> This is where the X Window system resides.