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authorDarren Hart <dvhart@linux.intel.com>2014-01-17 22:26:32 +0000
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-01-28 00:50:54 +0000
commit776a335d6a0ee1035057da392cc069b0e7d1a228 (patch)
tree52855ecc71a6944a4ce1cda81608a56d3a9135a5 /meta/conf
parente010be1367da53e9273d0501bbaffd1f605c5b5c (diff)
downloadpoky-776a335d6a0ee1035057da392cc069b0e7d1a228.tar.gz
tune: README: Document best practice
Describe the expected usage of base architecture tune files and arch-specific files, specifically the stacking of generations. (From OE-Core rev: 282735d7c8fcbd7e354f544c45461b095700fb77) Signed-off-by: Darren Hart <dvhart@linux.intel.com> Cc: Richard Purdie <richard.purdie@linuxfoundation.org> Cc: Paul Eggleton <paul.eggleton@intel.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Cc: Nitin Kamble <nitin.a.kamble@intel.com> Cc: Mark Hatle <mark.hatle@windriver.com> Cc: Bruce Ashfield <bruce.ashfield@windriver.com> Cc: Martin Jansa <martin.jansa@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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-rw-r--r--meta/conf/machine/include/README19
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diff --git a/meta/conf/machine/include/README b/meta/conf/machine/include/README
index 65d09428a8..6c390adeee 100644
--- a/meta/conf/machine/include/README
+++ b/meta/conf/machine/include/README
@@ -1,6 +1,9 @@
12012/03/30 - Mark Hatle <mark.hatle@windriver.com> 12012/03/30 - Mark Hatle <mark.hatle@windriver.com>
2 - Initial Revision 2 - Initial Revision
3 3
4
5Introduction
6============
4The individual CPU, and ABI tunings are contained in this directory. A 7The individual CPU, and ABI tunings are contained in this directory. A
5number of local and global variables are used to control the way the 8number of local and global variables are used to control the way the
6tunings are setup and how they work together to specify an optimized 9tunings are setup and how they work together to specify an optimized
@@ -79,3 +82,19 @@ configured in the same way that TUNE_CCARGS is.
79BASE_LIB_tune-<tune> - The "/lib" location for a specific ABI. This is 82BASE_LIB_tune-<tune> - The "/lib" location for a specific ABI. This is
80used in a multilib configuration to place the libraries in the correct, 83used in a multilib configuration to place the libraries in the correct,
81non-conflicting locations. 84non-conflicting locations.
85
86
87Best Practice
88=============
89The tune infrastructure is designed to be hierarchical. When writing a
90new tune file for a "fast-forward" CPU architecture (one that supports
91everything from a previous generation), it is recommended to require the
92previous generation tune file and specify PACKAGE_EXTRA_ARCHS using the
93previous generation's override and appending the new tune. Note that
94only one previous tune file should be included to avoid mutiple includes
95of the base arch which could lead to a broken configuration due to
96multiple prepend and append assignments.
97
98For example, for x86, there is a common x86/arch-x86.inc which is
99included in the base i586 tune file. The core2 tune builds
100on that, and corei7 builds on core2.