guix build: Add '--max-jobs' option.

Suggested by Deck Pickard <deck.r.pickard@gmail.com>.

* guix/scripts/build.scm (show-build-options-help): Document
  --max-jobs.
  (set-build-options-from-command-line): Pass #:max-build-jobs.
  (%standard-build-options): Add --max-jobs.
* doc/guix.texi (Invoking guix-daemon): Document the meaning of
  '--max-jobs 0'.
  (Invoking guix build): Document --max-jobs, with a reference to
  "Invoking guix-daemon'.

1 files changed, 9 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index a88b7747fc..fe1f8a8b76 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -596,7 +596,9 @@ parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
 @item --max-jobs=@var{n}
 @itemx -M @var{n}
 Allow at most @var{n} build jobs in parallel.  The default value is
-@code{1}.
+@code{1}.  Setting it to @code{0} means that no builds will be performed
+locally; instead, the daemon will offload builds (@pxref{Daemon Offload
+Setup}), or simply fail.
 
 @item --debug
 Produce debugging output.
@@ -2765,6 +2767,12 @@ may be helpful when debugging setup issues with the build daemon.
 Allow the use of up to @var{n} CPU cores for the build.  The special
 value @code{0} means to use as many CPU cores as available.
 
+@item --max-jobs=@var{n}
+@itemx -M @var{n}
+Allow at most @var{n} build jobs in parallel.  @xref{Invoking
+guix-daemon, @code{--max-jobs}}, for details about this option and the
+equivalent @command{guix-daemon} option.
+
 @end table
 
 Behind the scenes, @command{guix build} is essentially an interface to