From b88a3147639e3abbd2f007e40b2dd1ba21eb3f93 Mon Sep 17 00:00:00 2001
From: Angus Gratton <gus@projectgus.com>
Date: Fri, 17 Apr 2026 14:34:35 +1000
Subject: [PATCH] deps builld: Try to honour CMAKE_BUILD_PARALLEL_LEVEL
 (#13158)

* deps: Use CMAKE_BUILD_PARALLEL_LEVEL for dependency builds.

If set when initial CMake is run, don't hard-code the number of CPUs for all the
recursive child builds.

* build_linux: Pass -j1 for dependency build.

This is recommended by the comment at the top of deps/CMakeLists.txt, and makes
sense as the recursive build steps will pick up
CMAKE_BUILD_PARALLEL_LEVEL (otherwise the number of parallel jobs is squared).
---
 build_linux.sh      |  2 +-
 deps/CMakeLists.txt | 15 +++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/build_linux.sh b/build_linux.sh
index 45f0eebe8e..b23998b185 100755
--- a/build_linux.sh
+++ b/build_linux.sh
@@ -517,7 +517,7 @@ if [[ -n "${BUILD_DEPS}" ]] ; then
     fi
 
     print_and_run cmake -S deps -B deps/$BUILD_DIR "${CMAKE_C_CXX_COMPILER_CLANG[@]}" "${CMAKE_LLD_LINKER_ARGS[@]}" -G Ninja "${COLORED_OUTPUT}" "${BUILD_ARGS[@]}"
-    print_and_run cmake --build deps/$BUILD_DIR
+    print_and_run cmake --build deps/$BUILD_DIR -j1
 fi
 
 if [[ -n "${BUILD_ORCA}" ]] || [[ -n "${BUILD_TESTS}" ]] ; then
diff --git a/deps/CMakeLists.txt b/deps/CMakeLists.txt
index a90de994db..13bde6b307 100644
--- a/deps/CMakeLists.txt
+++ b/deps/CMakeLists.txt
@@ -166,11 +166,18 @@ function(orcaslicer_add_cmake_project projectname)
         endif ()
     endif ()
 
-    set(_gen "")
-    set(_build_j "-j${NPROC}")
     if (MSVC)
-        set(_gen CMAKE_GENERATOR "${DEP_MSVC_GEN}" CMAKE_GENERATOR_PLATFORM "${DEP_PLATFORM}")
-        set(_build_j "/m")
+      set(_gen CMAKE_GENERATOR "${DEP_MSVC_GEN}" CMAKE_GENERATOR_PLATFORM "${DEP_PLATFORM}")
+    else()
+      set(_gen "")
+    endif()
+
+    if ($ENV{CMAKE_BUILD_PARALLEL_LEVEL})
+      set(_build_j "")  # assume environment will control --build parallel setting
+    elseif(MSVC)
+      set(_build_j "/m")
+    else()
+      set(_build_j "-j${NPROC}")
     endif ()
 
 if (NOT IS_CROSS_COMPILE OR NOT APPLE)