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Diffstat (limited to 'documentation/adt-manual')
| -rw-r--r-- | documentation/adt-manual/adt-command.xml | 66 |
1 files changed, 45 insertions, 21 deletions
diff --git a/documentation/adt-manual/adt-command.xml b/documentation/adt-manual/adt-command.xml index d6fa8ee4d4..5df6a6f621 100644 --- a/documentation/adt-manual/adt-command.xml +++ b/documentation/adt-manual/adt-command.xml @@ -210,31 +210,55 @@ <title>Makefile-Based Projects</title> <para> - For Makefile-based projects, the cross-toolchain environment - variables established by running the cross-toolchain environment - setup script override any settings you might have in your - <filename>Makefile</filename>. - For example, if you had settings such as the following in your - <filename>Makefile</filename>, the environment variables defined - by the script would override them: + For Makefile-based projects, the cross-toolchain environment variables + established by running the cross-toolchain environment setup script + are subject to general <filename>make</filename> rules. + </para> + + <para> + To illustrate this, consider the following four cross-toolchain + environment variables: <literallayout class='monospaced'> - <ulink url='&YOCTO_DOCS_REF_URL;#var-CC'>CC</ulink>=arm-poky-linux-gnueabi-gcc - <ulink url='&YOCTO_DOCS_REF_URL;#var-LD'>LD</ulink>=arm-poky-linux-gnueabi-ld - <ulink url='&YOCTO_DOCS_REF_URL;#var-CFLAGS'>CFLAGS</ulink>=”${CFLAGS} --sysroot=<sysroot-dir>” - <ulink url='&YOCTO_DOCS_REF_URL;#var-CXXFLAGS'>CXXFLAGS</ulink>=”${CXXFLAGS} --sysroot=<sysroot-dir>” + <ulink url='&YOCTO_DOCS_REF_URL;#var-CC'>CC</ulink>=i586-poky-linux-gcc -m32 -march=i586 --sysroot=/opt/poky/1.8/sysroots/i586-poky-linux + <ulink url='&YOCTO_DOCS_REF_URL;#var-LD'>LD</ulink>=i586-poky-linux-ld --sysroot=/opt/poky/1.8/sysroots/i586-poky-linux + <ulink url='&YOCTO_DOCS_REF_URL;#var-CFLAGS'>CFLAGS</ulink>=-O2 -pipe -g -feliminate-unused-debug-types + <ulink url='&YOCTO_DOCS_REF_URL;#var-CXXFLAGS'>CXXFLAGS</ulink>=-O2 -pipe -g -feliminate-unused-debug-types </literallayout> - Consequently, you should not set variables like - <ulink url='&YOCTO_DOCS_REF_URL;#var-CC'><filename>CC</filename></ulink> - and - <ulink url='&YOCTO_DOCS_REF_URL;#var-LD'><filename>LD</filename></ulink> - in your <filename>Makefile</filename>. - For the list of variables set up by the cross-toolchain environment - setup script, see the - "<link linkend='setting-up-the-cross-development-environment'>Setting Up the Cross-Development Environment</link>" - section. + Now, consider the following three cases: + <itemizedlist> + <listitem><para><emphasis>Case 1 - No Variables Set in the <filename>Makefile</filename>:</emphasis> + Because these variables are not specifically set in the + <filename>Makefile</filename>, the variables retain their + values based on the environment. + </para></listitem> + <listitem><para><emphasis>Case 2 - Variables Set in the <filename>Makefile</filename>:</emphasis> + Specifically setting variables in the + <filename>Makefile</filename> during the build results in the + environment settings of the variables being overwritten. + </para></listitem> + <listitem><para><emphasis>Case 3 - Variables Set when the <filename>Makefile</filename> is Executed from the Command Line:</emphasis> + Executing the <filename>Makefile</filename> from the command + line results in the variables being overwritten with + command-line content regardless of what is being set in the + <filename>Makefile</filename>. + In this case, environment variables are not considered unless + you use the "-e" flag during the build: + <literallayout class='monospaced'> + $ make -e <replaceable>file</replaceable> + </literallayout> + If you use this flag, then the environment values of the + variables override any variables specifically set in the + <filename>Makefile</filename>. + </para></listitem> + </itemizedlist> + <note> + For the list of variables set up by the cross-toolchain environment + setup script, see the + "<link linkend='setting-up-the-cross-development-environment'>Setting Up the Cross-Development Environment</link>" + section. + </note> </para> </section> - </chapter> <!-- vim: expandtab tw=80 ts=4 |