A reliable port cross-build failure (hangup) in my context (amd64->armv7 cross build, with native-tool speedup involved)

[Mark Millard]

I had been reporting intermittent hang-ups for my amd64->{aarch64,armv7} port cross
builds in another message sequence. But it turns out that one thing I ran into
has hung-up every time, the same way, for amd64->armv7 cross builds:
multimedia/gstreamer1-qt at qt5 . So I extract the material here into a separate report
with some updated notes.

A little context: I had built from ports head -r484783 before under FreeBSD head
-r340287 (as I remember the version). Back then it did not have this problem that it
now has under FreeBSD head -r341836 . One ports-specific change was to force perl5.28
as the default instead of perl5.26 originally. In fact this is what drives what is
being rebuilt for my experiment that caught this. But I doubt the perl version is
important to the problem. The context has a Ryzen Threadripper 1950X and has been
tested both for FreeBSD under Hyper-V and for the same media native-booted. Both
hang-up at the same point as seen via ps or top. The native tools for cross-build
speedup were in use. Cross-builds targeting aarch64 did not get this problem but
targeting armv7 did. 121 of 129 armv7 ports built before the hang-up for the first
armv7 try.


The hang-up:

In the port rebuilds targeting armv7, multimedia/gstreamer1-qt at qt5 hung-up and timed
out. Looking during the wait in later tries shows something much like (from one of the
examples):

root       33719    0.0  0.0  12920  3528  0  I    11:40       0:00.03 | |           `-- sh: poudriere[FBSDFSSDjailArmV7-default][02]: build_pkg (gstreamer1-qt5-1.2.0_14) (sh)
root       41551    0.0  0.0  12920  3520  0  I    11:43       0:00.00 | |             `-- sh: poudriere[FBSDFSSDjailArmV7-default][02]: build_pkg (gstreamer1-qt5-1.2.0_14) (sh)
root       41552    0.0  0.0  10340  1744  0  IJ   11:43       0:00.01 | |               `-- /usr/bin/make -C /usr/ports/multimedia/gstreamer1-qt FLAVOR=qt5 build
root       41566    0.0  0.0  10236  1796  0  IJ   11:43       0:00.00 | |                 `-- /bin/sh -e -c (cd /wrkdirs/usr/ports/multimedia/gstreamer1-qt/work-qt5/.build; if ! /usr/bin/env QT_SELE
root       41567    0.0  0.0  89976 12896  0  IJ   11:43       0:00.07 | |                   `-- /usr/local/bin/qemu-arm-static ninja -j28 -v all
root       41585    0.0  0.0 102848 25056  0  IJ   11:43       0:00.10 | |                     |-- /usr/local/bin/qemu-arm-static /usr/local/bin/cmake -E cmake_autogen /wrkdirs/usr/ports/multimedia/g
root       41586    0.0  0.0 102852 25072  0  IJ   11:43       0:00.11 | |                     `-- /usr/local/bin/qemu-arm-static /usr/local/bin/cmake -E cmake_autogen /wrkdirs/usr/ports/multimedia/g

or as top showed it:

41552 root          1  52    0    10M  1744K    0 wait    15   0:00   0.00% /usr/bin/make -C /usr/ports/multimedia/gstreamer1-qt FLAVOR=qt5 build
41566 root          1  52    0    10M  1796K    0 wait     1   0:00   0.00% /bin/sh -e -c (cd /wrkdirs/usr/ports/multimedia/gstreamer1-qt/work-qt5/.build; if ! /usr/bin/env QT_SELECT=qt5 QMAKEMODULES
41567 root          2  52    0    88M    13M    0 select   4   0:00   0.00% /usr/local/bin/qemu-arm-static ninja -j28 -v all
41585 root          2  52    0   100M    24M    0 kqread   8   0:00   0.00% /usr/local/bin/qemu-arm-static /usr/local/bin/cmake -E cmake_autogen /wrkdirs/usr/ports/multimedia/gstreamer1-qt/work-qt5/.
41586 root          2  52    0   100M    24M    0 kqread  22   0:00   0.00% /usr/local/bin/qemu-arm-static /usr/local/bin/cmake -E cmake_autogen /wrkdirs/usr/ports/multimedia/gstreamer1-qt/work-qt5/.

So: waiting in kqread trying to run cmake.

Unlike some intermittent hang-ups, attaching-then-detaching via gdb does not
resume the hung-up processes. Kills of the processes waiting on kqread stop
the build.

Given the prior ports have been built already, building just
multimedia/gstreamer1-qt at qt5 still gets the hang-up at the same point.

Building anything that requires multimedia/gstreamer1-qt at qt5 seems to be
solidly blocked in my environment.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)