Complete support for ninja cmake backend by jgfouca · Pull Request #8532 · E3SM-Project/E3SM

jgfouca · 2026-07-02T19:06:57Z

With this PR, ninja is a usable CMake backend for E3SM. Ninja offers superior features to gmake with better parallelism, builds that terminate immediately when there's a failure, etc. If you want to try this feature, you can pass --ninja to create_test or change the default CMake backend for your machine, now represented by the config_machines.xml setting CMAKE_BACKEND to ninja.

Change list:

Includes a CIME update that only brings in better ninja support
Update build scripts to use flexible build invocation cmake --build instead of gmake.
Remove obsolete independent build scripts buildexe that appear to be tailored to the pre-cmake E3SM build system.
Make ninja the default for mappy
Update the ninja executable the comes bundled with E3SM.
Remove dangerous comment style in icepack

Fixes #6784

[BFB]

Copilot

Pull request overview

This pull request aims to make Ninja a usable CMake backend in E3SM by modernizing build script invocations (favoring cmake --build / cmake --install over direct gmake) and introducing a machine-configurable CMake backend selection.

Changes:

Switch several shared-library build scripts from gmake to cmake --build / cmake --install.
Add a new CMAKE_BACKEND build setting to driver component config and set mappy to default to ninja.
Remove obsolete buildexe scripts from both MOAB and MCT driver configs.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
share/build/buildlib.spio	Switch SCORPIO build invocation from `gmake` to `cmake --build`.
share/build/buildlib.gptl	Switch GPTL build/install from `gmake` to `cmake --build` / `cmake --install`.
share/build/buildlib.ekat	Switch EKAT build/install from `gmake` to `cmake --build` / `cmake --install`.
share/build/buildlib.csm_share	Switch csm_share build invocation from `gmake` to `cmake --build`.
driver-moab/cime_config/config_component.xml	Introduce `CMAKE_BACKEND` entry for MOAB driver build configuration.
driver-mct/cime_config/config_component.xml	Introduce `CMAKE_BACKEND` entry for MCT driver build configuration.
driver-moab/cime_config/buildexe	Remove obsolete standalone build script.
driver-mct/cime_config/buildexe	Remove obsolete standalone build script.
cime_config/machines/config_machines.xml	Set `mappy` machine default `CMAKE_BACKEND` to `ninja`.

jgfouca · 2026-07-02T19:14:43Z

    # This runs the pio make command from the cmake generated Makefile
    logger.info("Building SCORPIO")
-    run_bld_cmd_ensure_logging(f"{gmake} -j {gmake_j}", logger, from_dir=pio_bld_dir)
+    run_bld_cmd_ensure_logging(f"cmake --build . -v -j {gmake_j}", logger, from_dir=pio_bld_dir)


This is not true:
--parallel [<jobs>], -j [<jobs>]
-v, --verbose

+  <entry id="CMAKE_BACKEND">
+    <type>char</type>
+    <default_value>gmake</default_value>
+    <group>build_def</group>
+    <file>env_build.xml</file>
+    <desc>Tells cmake which backend to use</desc>
+  </entry>


+  <entry id="CMAKE_BACKEND">
+    <type>char</type>
+    <default_value>gmake</default_value>
+    <group>build_def</group>
+    <file>env_build.xml</file>
+    <desc>Tells cmake which backend to use</desc>
+  </entry>


Complete support for ninja cmake backend With this PR, ninja is a usable CMake backend for E3SM. Ninja offers superior features to gmake with better parallelism, builds that terminate immediately when there's a failure, etc. If you want to try this feature, you can pass --ninja to create_test or change the default CMake backend for your machine, now represented by the config_machines.xml setting CMAKE_BACKEND to ninja. Change list: 1) Includes a CIME update that only brings in better ninja support 2) Update build scripts to use flexible build invocation cmake --build instead of gmake. 3) Remove obsolete independent build scripts buildexe that appear to be tailored to the pre-cmake E3SM build system. 4) Make ninja the default for mappy 5) Update the ninja executable the comes bundled with E3SM. Fixes #6784 [BFB]

rljacob · 2026-07-03T19:32:25Z

can this option be used with create_newcase ?

rljacob · 2026-07-04T22:28:04Z

The switch the ninja appears to have created diffs in mappy testing. Please revert this from next if you can't explain/fix that.

This reverts commit 76e4639, reversing changes made to 88fc2c2. Unexplained diffs on mappy next

rljacob · 2026-07-06T02:10:49Z

reverted from next so we have a clean dashboard Monday.

jgfouca · 2026-07-06T14:56:38Z

@rljacob ,

can this option be used with create_newcase ?

There's no need. They can just add --ninja when they call case.build.

jgfouca · 2026-07-08T17:01:26Z

@jonbob , some small changes to ice stuff was needed.

jonbob · 2026-07-08T17:04:06Z

@jgfouca -- you had to change a line in the icepack submodule?

jgfouca · 2026-07-08T17:34:00Z

@jonbob , yep! It was a brutal debugging session. I explained the problem in the upstream PR I made:
CICE-Consortium/Icepack#562

jonbob · 2026-07-08T17:42:20Z

That would be really messy -- excellent sleuthing! So will this PR wait until the one into icepack gets merged?

jgfouca · 2026-07-08T17:53:28Z

@jonbob , thanks! I don't think we need to wait because I added the patch to our version. I made the upstream PR so that, whenever we update the submodule in the future, the fix will be there.

Complete support for ninja cmake backend With this PR, ninja is a usable CMake backend for E3SM. Ninja offers superior features to gmake with better parallelism, builds that terminate immediately when there's a failure, etc. If you want to try this feature, you can pass --ninja to create_test or change the default CMake backend for your machine, now represented by the config_machines.xml setting CMAKE_BACKEND to ninja. Change list: 1) Includes a CIME update that only brings in better ninja support 2) Update build scripts to use flexible build invocation cmake --build instead of gmake. 3) Remove obsolete independent build scripts buildexe that appear to be tailored to the pre-cmake E3SM build system. 4) Make ninja the default for mappy 5) Update the ninja executable the comes bundled with E3SM. 6) Remove dangerous comment style in icepack Fixes #6784 [BFB] * jgfouca/e3sm_ninja: Fix very subtle f90 comment cpp issue

This reverts commit a2a5996.

Bringing comment change introduced in E3SM-Project/E3SM#8532 into main. Fix unsafe comment

…t (PR #8582) Updating Icepack hash to main branch Updates Icepack submodule hash to point to main. The comment change introduced in #8532 changed the Icepack hash (E3SM-Project/Icepack@5d30e92) away from main. This change has been brought into the Icepack main branch in E3SM-Project/Icepack#44, so this PR has no code changes, only submodule hash update. [BFB]

Updating Icepack hash to main branch Updates Icepack submodule hash to point to main. The comment change introduced in #8532 changed the Icepack hash (E3SM-Project/Icepack@5d30e92) away from main. This change has been brought into the Icepack main branch in E3SM-Project/Icepack#44, so this PR has no code changes, only submodule hash update. [BFB]

jgfouca added 2 commits July 1, 2026 10:55

Update ninja executable

3e403bd

Full support for ninja

766d94f

jgfouca requested review from bartgol, Copilot, jasonb5, ndkeen and rljacob July 2, 2026 19:06

jgfouca self-assigned this Jul 2, 2026

jgfouca added Machine Files CIME CMake build system labels Jul 2, 2026

Copilot started reviewing on behalf of jgfouca July 2, 2026 19:07 View session

jgfouca requested a review from dqwu July 2, 2026 19:08

Copilot AI reviewed Jul 2, 2026

View reviewed changes

jgfouca mentioned this pull request Jul 2, 2026

E3SM CMake Build System V2! #5943

Open

41 of 50 tasks

jgfouca requested a review from jonbob July 2, 2026 19:17

bartgol approved these changes Jul 2, 2026

View reviewed changes

rljacob added a commit that referenced this pull request Jul 6, 2026

Revert "Merge branch 'jgfouca/e3sm_ninja' into next (PR #8532)"

a2a5996

This reverts commit 76e4639, reversing changes made to 88fc2c2. Unexplained diffs on mappy next

Fix very subtle f90 comment cpp issue

1208f7b

jgfouca added Icepack MPAS-seaice Concerning the MPAS-seaice model labels Jul 8, 2026

jgfouca added a commit that referenced this pull request Jul 16, 2026

Reapply "Merge branch 'jgfouca/e3sm_ninja' into next (PR #8532)"

2d1e725

This reverts commit a2a5996.

jgfouca merged commit a468e63 into master Jul 20, 2026

jgfouca deleted the jgfouca/e3sm_ninja branch July 20, 2026 18:14

amametjanov mentioned this pull request Jul 20, 2026

Use default binding of tasks to cores in non-xstrid PE-layouts on Frontier #8576

Merged

darincomeau mentioned this pull request Jul 23, 2026

Fix unsafe comment E3SM-Project/Icepack#44

Merged

11 tasks

darincomeau added a commit to E3SM-Project/Icepack that referenced this pull request Jul 23, 2026

Merge pull request #44 from E3SM-Project/fix-unsafe-comment

319653f

Bringing comment change introduced in E3SM-Project/E3SM#8532 into main. Fix unsafe comment

darincomeau mentioned this pull request Jul 23, 2026

Updating Icepack hash to main branch #8582

Merged

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Complete support for ninja cmake backend - #8532

Complete support for ninja cmake backend#8532
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