Being reproducibly built, Bitcoin Core semi-regularly turns up/suffers from
determinism issues in it's own code base, as well as in it's dependencies.
This is a non-exhaustive list of some of those issues.
ld64 is threaded, and uses a worker for each CPU to parse input files. However a
bug in the parser caused dependencies to be calculated differently based on
which files had already been parsed. As a result, builders with more CPUs were
more likely to see non-determinism.
Fixed in #9891
Examples:
TODO: Determine in exactly which version of ld64 this was fixed.
In version 1.0.1j OpenSSL would embed a timestamp using
echo " #define DATE \"`LC_ALL=C LC_TIME=C date`\""; \
This behaviour was in crypto/Makefile.
From 1.0.1k, the behaviour moved into util/mkbuildinf.pl.
Fixed after the 1.0.1k bump in c3200bcd1e7116e079aebabed3a01dc5385bfc9e.
A symbol ordering issue, libstdc++.so.6 and __gmon_start__ appeared to be
swapped, in protoc on win32 systems caused non-determinism.
Issue discussion in #3725.
Fixed in #3742.
Including the Makefile in the NSIS genearated documentation was causing
determinism issues depending on wether certain programs (gawk & mawk) were
available on the build VM.
Fixed in #14018
Examples:
Qt's configure grabs the path to the xkb data root during configure. Build
changes in Qt 5.8 broke the handling for cross-builds. This caused the string
embedded in the binary to differ depending on wether certain files were present
in the builders filesystem.
Fixed in #14000
After the bump to Qt 5.9, the rcc tool was embedding timestamps
into build output. This resulted in qrc_bitcoin_locale.cpp always being
generated in a non-deterministic way.
Upstream issue QTBUG-62511
Fixed in #13732
During the gitian builds for the 0.20.0 release luke-jr noticed that his
bitcoin-osx-unsigned.tar.gz was not matching anyone elses. The cause was
determined to be a small difference in the genisoimage binary. IRC discussion
available here.
### ./genisoimage
```diff
@@ -49796,16 +49796,16 @@
000c2830: 6400 7573 616c 6f5f 6169 7361 7461 7069 d.usalo_aisatapi
000c2840: 0075 7361 6c6f 5f61 7265 7365 7400 7363 .usalo_areset.sc
000c2850: 616e 5f69 6e74 6572 6e61 6c00 7367 5f61 an_internal.sg_a
000c2860: 6d61 7064 6576 0075 7361 6c6f 5f61 6765 mapdev.usalo_age
000c2870: 745f 6669 7273 745f 6672 6565 5f73 6869 t_first_free_shi
000c2880: 6c6c 7962 7573 0075 7361 6c6f 5f61 6d65 llybus.usalo_ame
000c2890: 7267 6500 7367 5f61 6d61 7064 6576 5f73 rge.sg_amapdev_s
-000c28a0: 6373 6900 6b76 2e36 3034 3100 7761 726e csi.kv.6041.warn
-000c28b0: 5f73 7973 6673 2e36 3036 3300 7367 5f63 _sysfs.6063.sg_c
+000c28a0: 6373 6900 6b76 2e36 3034 3400 7761 726e csi.kv.6044.warn
+000c28b0: 5f73 7973 6673 2e36 3036 3600 7367 5f63 _sysfs.6066.sg_c
000c28c0: 6c65 6172 6e62 6c6f 636b 0073 675f 6d61 learnblock.sg_ma
000c28d0: 7064 6576 0073 675f 7365 7475 7000 7367 pdev.sg_setup.sg
000c28e0: 5f6d 6170 6275 7300 7367 5f69 6e69 7464 _mapbus.sg_initd
000c28f0: 6576 0073 675f 7365 7474 696d 656f 7574 ev.sg_settimeout
000c2900: 0073 675f 7261 6973 6564 6d61 0066 7265 .sg_raisedma.fre
000c2910: 6164 7374 7269 6e67 0073 675f 6765 7469 adstring.sg_geti
000c2920: 6e74 0073 675f 7277 7365 6e64 0075 7361 nt.sg_rwsend.usamingw linker leaking bytes, causing non-determinism.
bitcoin/bitcoin#6900
cdrkit determinism patch
dont add . to tar list - bitcoin/bitcoin#5790