[v7,4/8] Makefile: allow top-level parallel build with BR2_PER_PACKAGE_DIRECTORIES=y
diff mbox series

Message ID 20181228104335.22379-5-thomas.petazzoni@bootlin.com
State Superseded
Headers show
Series
  • Top-level parallel build support
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Commit Message

Thomas Petazzoni Dec. 28, 2018, 10:43 a.m. UTC
With per-package folder support, top-level parallel build becomes
safe, so we can enclose the .NOTPARALLEL statement in a
!BR2_PER_PACKAGE_DIRECTORIES condition.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 Makefile | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

Comments

Yann E. MORIN Dec. 28, 2018, 12:51 p.m. UTC | #1
Thomas, All,

On 2018-12-28 11:43 +0100, Thomas Petazzoni spake thusly:
> With per-package folder support, top-level parallel build becomes
> safe, so we can enclose the .NOTPARALLEL statement in a
> !BR2_PER_PACKAGE_DIRECTORIES condition.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

> ---
>  Makefile | 19 +++++--------------
>  1 file changed, 5 insertions(+), 14 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index e01ec4c963..74c0757fd8 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -228,21 +228,12 @@ ifeq ($(filter $(noconfig_targets),$(MAKECMDGOALS)),)
>  -include $(BR2_CONFIG)
>  endif
>  
> -# Parallel execution of this Makefile is disabled because it changes
> -# the packages building order, that can be a problem for two reasons:
> -# - If a package has an unspecified optional dependency and that
> -#   dependency is present when the package is built, it is used,
> -#   otherwise it isn't (but compilation happily proceeds) so the end
> -#   result will differ if the order is swapped due to parallel
> -#   building.
> -# - Also changing the building order can be a problem if two packages
> -#   manipulate the same file in the target directory.
> -#
> -# Taking into account the above considerations, if you still want to execute
> -# this top-level Makefile in parallel comment the ".NOTPARALLEL" line and
> -# use the -j<jobs> option when building, e.g:
> -#      make -j$((`getconf _NPROCESSORS_ONLN`+1))
> +ifeq ($(BR2_PER_PACKAGE_DIRECTORIES),)
> +# Disable top-level parallel build if per-package directories is not
> +# used. Indeed, per-package directories is necessary to guarantee
> +# determinism and reproducibility with top-level parallel build.
>  .NOTPARALLEL:
> +endif
>  
>  # timezone and locale may affect build output
>  ifeq ($(BR2_REPRODUCIBLE),y)
> -- 
> 2.20.1
>

Patch
diff mbox series

diff --git a/Makefile b/Makefile
index e01ec4c963..74c0757fd8 100644
--- a/Makefile
+++ b/Makefile
@@ -228,21 +228,12 @@  ifeq ($(filter $(noconfig_targets),$(MAKECMDGOALS)),)
 -include $(BR2_CONFIG)
 endif
 
-# Parallel execution of this Makefile is disabled because it changes
-# the packages building order, that can be a problem for two reasons:
-# - If a package has an unspecified optional dependency and that
-#   dependency is present when the package is built, it is used,
-#   otherwise it isn't (but compilation happily proceeds) so the end
-#   result will differ if the order is swapped due to parallel
-#   building.
-# - Also changing the building order can be a problem if two packages
-#   manipulate the same file in the target directory.
-#
-# Taking into account the above considerations, if you still want to execute
-# this top-level Makefile in parallel comment the ".NOTPARALLEL" line and
-# use the -j<jobs> option when building, e.g:
-#      make -j$((`getconf _NPROCESSORS_ONLN`+1))
+ifeq ($(BR2_PER_PACKAGE_DIRECTORIES),)
+# Disable top-level parallel build if per-package directories is not
+# used. Indeed, per-package directories is necessary to guarantee
+# determinism and reproducibility with top-level parallel build.
 .NOTPARALLEL:
+endif
 
 # timezone and locale may affect build output
 ifeq ($(BR2_REPRODUCIBLE),y)