build system: allow arbitrary specification of number of cores used

Use NPROC=foo
Replace "foo" with a number. By default, the build system uses $(nproc).
This patch allows the user to specify any number of cores. This is useful
on some systems, or certain chroot environments.

1 files changed, 12 insertions, 1 deletions

diff --git a/resources/scripts/helpers/build/module/grub b/resources/scripts/helpers/build/module/grub
index f899bc2..5b2c7a6 100755
--- a/resources/scripts/helpers/build/module/grub
+++ b/resources/scripts/helpers/build/module/grub
@@ -24,6 +24,17 @@
 
 [ "x${DEBUG+set}" = 'xset' ] && set -v
 set -u -e
+if [ -z ${NPROC+x} ]; then
+    cores="$(nproc)"
+else
+    case ${NPROC} in
+        ''|*[!0-9]*)
+            printf "value '%s' for NPROC is invalid. non-numeric. Exiting.\n" "${NPROC}"
+            exit 1
+            ;;
+    esac
+    cores="${NPROC}"
+fi
 
 # Build GRUB2 as coreboot payload
 
@@ -39,5 +50,5 @@ cd grub/
 # build
 ./autogen.sh
 ./configure --with-platform=coreboot
-make -j$(nproc)
+make -j${cores}
 )