使用CMake构建外部项目时，jobserver不可用 [英] jobserver unavailable when building external projects with CMake

问题描述

我正在尝试使用ExternalProject_add在Linux上使用CMake构建一些外部项目.但是，他们不遵守make -j12命令，并发出警告:

I'm trying to build some external projects with CMake on linux using ExternalProject_add. However, they aren't respecting the make -j12 command, and are giving the warning:

‘warning: jobserver unavailable: using -j1. Add `+' to parent make rule.’

这使我的构建速度减慢了.有什么办法可以并行构建外部项目?这是一个示例项目:

This slows my build painfully. Is there some way to build external projects in parallel? Here's an example project:

include(ExternalProject)
    ExternalProject_Add(
        ${TARGET_NAME}-ext
        URL ${CMAKE_CURRENT_SOURCE_DIR}/xerces-c-${VERSION_XERCESC}.tar.gz
        DOWNLOAD_DIR ${XERCESC_DIR}
        SOURCE_DIR ${XERCESC_DIR}/src
        PATCH_COMMAND chmod guo+rw ${CMAKE_CURRENT_SOURCE_DIR} -R
        CONFIGURE_COMMAND ./configure --prefix=${XERCESC_DIR} --disable-shared -q --disable-network --enable-transcoder-gnuiconv --enable-msgloader-inmemory
        BUILD_COMMAND make --silent
        INSTALL_COMMAND make install
        BUILD_IN_SOURCE 1
    )

推荐答案

为了允许make命令正确传播到其子级，您需要在括号中使用$(MAKE)(而不是大括号)，而不是按照命令进行操作，即

In order to allow the make commands to properly propagate to their children, you need to use $(MAKE) with parenthesis (not curly-braces) instead of make as your command, i.e.

BUILD_COMMAND $(MAKE) --silent
INSTALL_COMMAND $(MAKE) install

从CMake 2.8.4版开始支持此功能.

This is supported from CMake version 2.8.4 onward.

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