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authorLudovic Courtès <ludo@gnu.org>2015-12-08 23:27:53 +0100
committerLudovic Courtès <ludo@gnu.org>2015-12-08 23:58:12 +0100
commit5b74fe065b33ee99372d472f2d6ee5284d720b75 (patch)
treef71f8b3bf34e65c08a794492ab22a7684326c65c /doc/contributing.texi
parent2fba87ac7c3e6fc6ca1a6e94131303c37425b2ba (diff)
downloadguix-5b74fe065b33ee99372d472f2d6ee5284d720b75.tar
guix-5b74fe065b33ee99372d472f2d6ee5284d720b75.tar.gz
guix build: Add '--rounds'.
* guix/scripts/build.scm (show-build-options-help) (%standard-build-options): Add --rounds. (set-build-options-from-command-line): Honor it. * doc/guix.texi (Invoking guix build): Document it. * doc/contributing.texi (Submitting Patches): Mention it.
Diffstat (limited to 'doc/contributing.texi')
-rw-r--r--doc/contributing.texi26
1 files changed, 21 insertions, 5 deletions
diff --git a/doc/contributing.texi b/doc/contributing.texi
index a66f5374b9..b61f6a534c 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -279,15 +279,31 @@ not affected by the change; @code{guix refresh --list-dependent
@var{package}} will help you do that (@pxref{Invoking guix refresh}).
@item
+@cindex determinism, of build processes
+@cindex reproducible builds, checking
Check whether the package's build process is deterministic. This
typically means checking whether an independent build of the package
yields the exact same result that you obtained, bit for bit.
-A simple way to do that is with @command{guix challenge}
-(@pxref{Invoking guix challenge}). You may run it once the package has
-been committed and built by @code{hydra.gnu.org} to check whether it
-obtains the same result as you did. Better yet: Find another machine
-that can build it and run @command{guix publish}.
+A simple way to do that is by building the same package several times in
+a row on your machine (@pxref{Invoking guix build}):
+
+@example
+guix build --rounds=2 my-package
+@end example
+
+This is enough to catch a class of common non-determinism issues, such
+as timestamps or randomly-generated output in the build result.
+
+Another option is to use @command{guix challenge} (@pxref{Invoking guix
+challenge}). You may run it once the package has been committed and
+built by @code{hydra.gnu.org} to check whether it obtains the same
+result as you did. Better yet: Find another machine that can build it
+and run @command{guix publish}. Since the remote build machine is
+likely different from yours, this can catch non-determinism issues
+related to the hardware---e.g., use of different instruction set
+extensions---or to the operating system kernel---e.g., reliance on
+@code{uname} or @file{/proc} files.
@end enumerate