core/pkg-cmake: do not build host-cmake if not needed (branch yem/host-cmake)

From: Luca Ceresoli <[email protected]>

Currently all cmake packages depend on host-cmake. Unfortunately host-cmake takes a long time to configure and build: almost 7 minutes on a dual-core i5 with SSD. The time does not change even with ccache enabled.

Indeed, building host-cmake is avoidable if it is already installed on the build host: CMake is supposed to be quite portable, and the only patch in Buildroot for the CMake package seems to only affect target-cmake.

Thus we automatically skip building host-cmake and use the one on the system if:
- cmake is available on the system and
- it is recent enough.

First, we leverage the existing infrastructure in support/dependencies/dependencies.mk to find out whether there's a suitable cmake executable on the system. Its path can be passed in the BR2_CMAKE environment variable, otherwise it defaults to "cmake". If it is enabled, found and suitable then we set BR2_CMAKE_HOST_DEPENDENCY to empty; otherwise we set BR2_CMAKE_HOST_DEPENDENCY to 'host-cmake' and override BR2_CMAKE with "$(HOST_DIR)/usr/bin/cmake" to revert to using our own cmake (the old behaviour).

Then in pkg-cmake.mk we replace the hard-coded dependency on host-cmake to using the BR2_CMAKE_HOST_DEPENDENCY variable, and we use $(BR2_CMAKE) instead of $(HOST_DIR)/usr/bin/cmake.

Unlike what we do for host-tar and host-xzcat, for host-cmake we do not add host-cmake to DEPENDENCIES_HOST_PREREQ. If we did, host-cmake would be a dependency for _any_ package when it's not installed on the host, even when no cmake package is selected.

Cmake versions older than 3.0 are affected by the bug described and fixed in Buildroot in ef2c1970e4bf ("cmake: add patch to fix Qt mkspecs detection"). The bug was fixed in upstream CMake in version 3.0 [0].

Amongst all the cmake packages currently in Buildroot, the currently highest version mentioned in cmake_minimum_required() is 3.1 (grantlee and opencv3).

Thus we use 3.1 as the lowest required cmake for now, until a package is bumped, or a new package added, with a higher required version.

[0] https://cmake.org/gitweb?p=cmake.git;h=e8b8b37ef6fef094940d3384df5a1d421b9fa568

Signed-off-by Luca Ceresoli <[email protected]>

Cc Samuel Martin <[email protected]>

Cc Davide Viti <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Cc Thomas Petazzoni <[email protected]>

Reviewed-by Romain Naour <[email protected]>

Tested-by Romain Naour <[email protected]>

[yann.morin.1998 at free.fr:
- simplify logic in check-host-cmake.mk;
- set and use BR2_CMAKE_HOST_DEPENDENCY, drop USE_SYSTEM_CMAKE;
- bump to cmake 3.1 for grantlee and opencv;
]

Signed-off-by Yann E. MORIN <[email protected]>

---
Results (by Luca, before Yann's changes):

On my build server, this patch reduced the build time for a batch of 16 Buildroot configurations (all building cmake-based packages) from 2h44m to 1h54m. Woah, it's a 30% saving!

Tested on:
- Ubuntu 14.04 without CMake, with official CMake (2.8), PPA CMake (3.2)
- Ubuntu 15.10 without CMake, with official CMake (3.2)
- Ubuntu 16.04 without CMake, with official CMake (3.5)

Results (by Yann):

On my machine, this gains about 5min 30s per build, which is far from negligible.

Tested, by artificially bumping/lowering the minimum required version, on:
- Ubuntu 16.04 without CMake, with official CMake (3.5)

---
Changes v7 -> v8:
- handle versions in three parts (X.Y>Z) (Arnout)

Changes v6 -> v7:
- drop the post-patch hook, moved to a follow-up patch (Arnout)
- eye-candy in script (Arnout)

Changes v5 -> v6:
- rename variables in the version check in pkg-cmake (Luca)
- fix commit log (Luca)

Changes v4 -> v5:
- adopted by Yann;
- drop USE_SYSTEM_CMAKE in favour of BR2_CMAKE_HOST_DEPENDENCY which directly contains 'host-cmake' if it is needed;
- unconditionally add $(BR2_CMAKE_HOST_DEPENDENCY) to dependencies: it is empty if host-cmake is not needed;
- check our minimum version is enough in a post-patch hook.

Changes v3 -> v4:
- rename USE_SYSTEM_HOST_CMAKE -> USE_SYSTEM_CMAKE (Arnout)
- ditch BR2_TRY_SYSTEM_CMAKE and use system-cmake unconditionally if it is found and >= 3.0 (Arnout)
- rename BR2_HOST_CMAKE -> BR2_CMAKE since it can be either a host-cmake (built by Buildroot) or a system-cmake

Changes v2 -> v3:
- make this feature optional via the BR2_TRY_SYSTEM_CMAKE kconfig variable
- rename the CMAKE variable to BR2_HOST_CMAKE, so it's coherent with the naming of other variables overridable by the environment, e.g. BR2_DL_DIR
- invert the logic of the variable triggering the host-cmake
dependency: USE_SYSTEM_CMAKE instead of BUILD_HOST_CMAKE; needed to implement BR2_TRY_SYSTEM_CMAKE

Changes v1 -> v2:
- Require cmake >= 3.0. Fixes qjson failure (Luca, Samuel, Thomas)
- In check-host-cmake.sh only search $1, not "cmake" (Arnout)
- typo: host-ccache -> host-cmake (Arnout)

---
 package/pkg-cmake.mk                     |  6 ++---
 support/dependencies/check-host-cmake.mk | 18 +++++++++++++++
 support/dependencies/check-host-cmake.sh | 39 ++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 3 deletions(-)
 create mode 100644 support/dependencies/check-host-cmake.mk
 create mode 100755 support/dependencies/check-host-cmake.sh

package/pkg-cmake.mk +3 -3

index 4c6dc62..aca9e61 100644
@@ -85,7 +85,7 @@ define $(2)_CONFIGURE_CMDS
 	cd $$($$(PKG)_BUILDDIR) && \
 	rm -f CMakeCache.txt && \
 	PATH=$$(BR_PATH) \
-	$$($$(PKG)_CONF_ENV) $$(HOST_DIR)/usr/bin/cmake $$($$(PKG)_SRCDIR) \
+	$$($$(PKG)_CONF_ENV) $$(BR2_CMAKE) $$($$(PKG)_SRCDIR) \
 		-DCMAKE_TOOLCHAIN_FILE="$$(HOST_DIR)/usr/share/buildroot/toolchainfile.cmake" \
 		-DCMAKE_BUILD_TYPE=$$(if $$(BR2_ENABLE_DEBUG),RelWithDebInfo,Release) \
 		-DCMAKE_INSTALL_PREFIX="/usr" \

@@ -110,7 +110,7 @@ define $(2)_CONFIGURE_CMDS
 	cd $$($$(PKG)_BUILDDIR) && \
 	rm -f CMakeCache.txt && \
 	PATH=$$(BR_PATH) \
-	$$(HOST_DIR)/usr/bin/cmake $$($$(PKG)_SRCDIR) \
+	$$(BR2_CMAKE) $$($$(PKG)_SRCDIR) \
 		-DCMAKE_INSTALL_SO_NO_EXE=0 \
 		-DCMAKE_FIND_ROOT_PATH="$$(HOST_DIR)" \
 		-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM="BOTH" \

@@ -146,7 +146,7 @@ endif
 # primitives to find {C,LD}FLAGS, add it to the dependency list.
 $(2)_DEPENDENCIES += host-pkgconf
 
-$(2)_DEPENDENCIES += host-cmake
+$(2)_DEPENDENCIES += $(BR2_CMAKE_HOST_DEPENDENCY)
 
 #
 # Build step. Only define it if not already defined by the package .mk

support/dependencies/check-host-cmake.mk new file +18 -0

new file mode 100644
index 0000000..8002278
@@ -0,0 +1,18 @@
+# Versions before 3.0 are affected by the bug described in
+# https://git.busybox.net/buildroot/commit/?id=ef2c1970e4bff3be3992014070392b0e6bc28bd2
+# and fixed in upstream CMake in version 3.0:
+# https://cmake.org/gitweb?p=cmake.git;h=e8b8b37ef6fef094940d3384df5a1d421b9fa568
+#
+# Set this to either 3.0 or higher, depending on the highest minimum
+# version required by any of the packages bundled in Buildroot. If a
+# package is bumped or a new one added, and it requires a higher
+# version, our cmake infra will catch it and whine.
+#
+BR2_CMAKE_VERSION_MIN = 3.1
+
+BR2_CMAKE ?= cmake
+ifeq ($(call suitable-host-package,cmake,\
+	$(BR2_CMAKE) $(BR2_CMAKE_VERSION_MIN)),)
+BR2_CMAKE = $(HOST_DIR)/usr/bin/cmake
+BR2_CMAKE_HOST_DEPENDENCY = host-cmake
+endif

support/dependencies/check-host-cmake.sh new file +18 -0

new file mode 100755
index 0000000..9b63b06
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+candidate="${1}"
+version_min="${2}"
+
+major_min="${version_min%.*}"
+minor_min="${version_min#*.}"
+
+cmake=`which ${candidate}`
+if [ ! -x "${cmake}" ]; then
+    # echo nothing: no suitable cmake found
+    exit 1
+fi
+
+# Extract version X.Y from versions in the form X.Y or X.Y.Z
+# with X, Y and Z numbers with one or more digits each, e.g.
+#   3.2     -> 3.2
+#   3.2.3   -> 3.2

Quoted 5 lines

From: Luca Ceresoli <[email protected]>
Currently all cmake packages depend on host-cmake. Unfortunately host-cmake takes a long time to configure and build: almost 7 minutes on a dual-core i5 with SSD. The time does not change even with ccache enabled.

Quoted 28 lines

support/dependencies/check-host-cmake.sh new file +22 -0

new file mode 100755
index 0000000..9b63b06
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+candidate="${1}"
+version_min="${2}"
+
+major_min="${version_min%.*}"
+minor_min="${version_min#*.}"
+
+cmake=`which ${candidate}`
+if [ ! -x "${cmake}" ]; then
+    # echo nothing: no suitable cmake found
+    exit 1
+fi
+
+# Extract version X.Y from versions in the form X.Y or X.Y.Z
+# with X, Y and Z numbers with one or more digits each, e.g.
+#   3.2     -> 3.2
+#   3.2.3   -> 3.2
+#   3.2.42  -> 3.2
+#   3.10    -> 3.10
+#   3.10.4  -> 3.10
+#   3.10.42 -> 3.10

support/dependencies/check-host-cmake.sh line 28

Quoted 6 lines

support/dependencies/check-host-cmake.sh new file +6 -0

+version="$(${cmake} --version \
+           |sed -r -e '/.* ([[:digit:]]+\.[[:digit:]]+).*$/!d;' \
+                   -e 's//\1/'
+          )"
+major="${version%.*}"
+minor="${version#*.}"

You removed the 'head -n1' in the pipe.

Luca, All,

On 2016-09-13 23:05 +0200, Luca Ceresoli spake thusly:

Quoted 6 lines · Yann E. MORIN

Quoted 5 lines

From: Luca Ceresoli <[email protected]>
Currently all cmake packages depend on host-cmake. Unfortunately host-cmake takes a long time to configure and build: almost 7 minutes on a dual-core i5 with SSD. The time does not change even with ccache enabled.

[--SNIP--]

Quoted 28 lines

Quoted 28 lines

support/dependencies/check-host-cmake.sh new file +22 -0

new file mode 100755
index 0000000..9b63b06
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+candidate="${1}"
+version_min="${2}"
+
+major_min="${version_min%.*}"
+minor_min="${version_min#*.}"
+
+cmake=`which ${candidate}`
+if [ ! -x "${cmake}" ]; then
+    # echo nothing: no suitable cmake found
+    exit 1
+fi
+
+# Extract version X.Y from versions in the form X.Y or X.Y.Z
+# with X, Y and Z numbers with one or more digits each, e.g.
+#   3.2     -> 3.2
+#   3.2.3   -> 3.2
+#   3.2.42  -> 3.2
+#   3.10    -> 3.10
+#   3.10.4  -> 3.10
+#   3.10.42 -> 3.10

Quoted 8 lines

support/dependencies/check-host-cmake.sh line 28

Quoted 6 lines

support/dependencies/check-host-cmake.sh new file +6 -0

+version="$(${cmake} --version \
+           |sed -r -e '/.* ([[:digit:]]+\.[[:digit:]]+).*$/!d;' \
+                   -e 's//\1/'
+          )"
+major="${version%.*}"
+minor="${version#*.}"

You removed the 'head -n1' in the pipe.

Indeed, but look at the sed script (which is not that complicated): all lines that do not match the pattern are ignored.

        |sed -r -e '/.* ([[:digit:]]+\.[[:digit:]]+).*$/!d;' \
                                               Here ----^

"!d" means "if no match, delete line".

Then the next expression is only aplied on matching lines, and "\1" refers to the ()-match, which is the version string.

Regards,
Yann E. MORIN.

Quoted 50 lines · Yann E. MORIN

Luca, All,

On 2016-09-13 23:05 +0200, Luca Ceresoli spake thusly:

Quoted 6 lines · Yann E. MORIN

Quoted 5 lines

From: Luca Ceresoli <[email protected]>
Currently all cmake packages depend on host-cmake. Unfortunately host-cmake takes a long time to configure and build: almost 7 minutes on a dual-core i5 with SSD. The time does not change even with ccache enabled.

[--SNIP--]

Quoted 28 lines

Quoted 28 lines

support/dependencies/check-host-cmake.sh new file +22 -0

new file mode 100755
index 0000000..9b63b06
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+candidate="${1}"
+version_min="${2}"
+
+major_min="${version_min%.*}"
+minor_min="${version_min#*.}"
+
+cmake=`which ${candidate}`
+if [ ! -x "${cmake}" ]; then
+    # echo nothing: no suitable cmake found
+    exit 1
+fi
+
+# Extract version X.Y from versions in the form X.Y or X.Y.Z
+# with X, Y and Z numbers with one or more digits each, e.g.
+#   3.2     -> 3.2
+#   3.2.3   -> 3.2
+#   3.2.42  -> 3.2
+#   3.10    -> 3.10
+#   3.10.4  -> 3.10
+#   3.10.42 -> 3.10

Quoted 8 lines

support/dependencies/check-host-cmake.sh line 28

Quoted 6 lines

support/dependencies/check-host-cmake.sh new file +6 -0

+version="$(${cmake} --version \
+           |sed -r -e '/.* ([[:digit:]]+\.[[:digit:]]+).*$/!d;' \
+                   -e 's//\1/'
+          )"
+major="${version%.*}"
+minor="${version#*.}"

You removed the 'head -n1' in the pipe.

Indeed, but look at the sed script (which is not that complicated): all lines that do not match the pattern are ignored.

Quoted 7 lines

        |sed -r -e '/.* ([[:digit:]]+\.[[:digit:]]+).*$/!d;' \
                                               Here ----^

"!d" means "if no match, delete line".

Then the next expression is only aplied on matching lines, and "\1" refers to the ()-match, which is the version string.

You snipped away Luca's example: if there are two lines that contain something
that looks like a version number, then you get two versions out of this script. So repeating Luca's example:

cmake version 3.5.1

Linked against libfoobar 7.6.5

will give you

version="3.5
7.6"

From: Luca Ceresoli <[email protected]>

Currently all cmake packages depend on host-cmake. Unfortunately host-cmake takes a long time to configure and build: almost 7 minutes on a dual-core i5 with SSD. The time does not change even with ccache enabled.

Indeed, building host-cmake is avoidable if it is already installed on the build host: CMake is supposed to be quite portable, and the only patch in Buildroot for the CMake package seems to only affect target-cmake.

Thus we automatically skip building host-cmake and use the one on the system if:
- cmake is available on the system and
- it is recent enough.

First, we leverage the existing infrastructure in support/dependencies/dependencies.mk to find out whether there's a suitable cmake executable on the system. Its path can be passed in the BR2_CMAKE environment variable, otherwise it defaults to "cmake". If it is enabled, found and suitable then we set BR2_CMAKE_HOST_DEPENDENCY to empty; otherwise we set BR2_CMAKE_HOST_DEPENDENCY to 'host-cmake' and override BR2_CMAKE with "$(HOST_DIR)/usr/bin/cmake" to revert to using our own cmake (the old behaviour).

Then in pkg-cmake.mk we replace the hard-coded dependency on host-cmake to using the BR2_CMAKE_HOST_DEPENDENCY variable, and we use $(BR2_CMAKE) instead of $(HOST_DIR)/usr/bin/cmake.

Unlike what we do for host-tar and host-xzcat, for host-cmake we do not add host-cmake to DEPENDENCIES_HOST_PREREQ. If we did, host-cmake would be a dependency for _any_ package when it's not installed on the host, even when no cmake package is selected.

Cmake versions older than 3.0 are affected by the bug described and fixed in Buildroot in ef2c1970e4bf ("cmake: add patch to fix Qt mkspecs detection"). The bug was fixed in upstream CMake in version 3.0 [0].

Amongst all the cmake packages currently in Buildroot, the currently highest version mentioned in cmake_minimum_required() is 3.1 (grantlee and opencv3).

Thus we use 3.1 as the lowest required cmake for now, until a package is bumped, or a new package added, with a higher required version.

[0] https://cmake.org/gitweb?p=cmake.git;h=e8b8b37ef6fef094940d3384df5a1d421b9fa568

Signed-off-by Luca Ceresoli <[email protected]>

Cc Samuel Martin <[email protected]>

Cc Davide Viti <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Cc Thomas Petazzoni <[email protected]>

Reviewed-by Romain Naour <[email protected]>

Tested-by Romain Naour <[email protected]>

[yann.morin.1998 at free.fr:
- simplify logic in check-host-cmake.mk;
- set and use BR2_CMAKE_HOST_DEPENDENCY, drop USE_SYSTEM_CMAKE;
- bump to cmake 3.1 for grantlee and opencv;
]

Signed-off-by Yann E. MORIN <[email protected]>

---
Results (by Luca, before Yann's changes):

If the existing host cmake is deemed usable, we now skip building our own variant.

However, in the following conditions, the build would fail:

- host cmake: 3.2
- Buildroot requirement: 3.1
- package requirement: 3.4
- cmake package in Buildroot: 3.5

This is because Buildroot would consider that cmake-3.2 is usable (and it technically is for Buildroot, which requires 3.0), but the package will fail at configure time.

To catch this situation and fix Buildroot, we add a post-patch hook that checks that, amongst all cmake versions required by the package, the version required by Buildroot is at least equal or higher.

We do use a post-patch hook rather than the more expected pre-configure hook, to avoid having to build all the package dependencies just to check the cmake version.

Exclude the cmake (target variant) from that check, since it requires cmake >= 3.4. However, that requirement is only for the tests, and we're not building them; all the other parts of the build have no requirement besides a cmake >= 2.8). Bumping the version Buildroot requires to 3.4 would almost always defeat the purpose of this change, as a lot of not-so-old distributions are still using cmake < 3.4; only very recent ones released since the end of 2015 would stand a chance of having such a cmake version. So we just exclude cmake from that check.

Signed-off-by "Yann E. MORIN" <[email protected]>

Cc Luca Ceresoli <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Cc Samuel Martin <[email protected]>

Cc Thomas Petazzoni <[email protected]>

Cc Davide Viti <[email protected]>

Reviewed-by Arnout Vandecappelle (Essensium/Mind) <[email protected]>