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authorGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-02-02 16:31:21 +0100
committerGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-02-06 11:16:00 +0100
commit508c3e0c50c836f03b26cf08b96310e783830744 (patch)
treeffe4c9f5f8662a47642162bd26d36ac1cc298f3d /docs
parent6856e417da4f3aa77e2a814db2a89429af072f7d (diff)
downloadbuildroot-508c3e0c50c836f03b26cf08b96310e783830744.tar.gz
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docs/manual: document usage of BR2_TOOLCHAIN_HAS_SYNC_x
This commit updates the documentation to detail when and how to use the BR2_TOOLCHAIN_HAS_SYNC_x dependency. Note that we chose to not add a comment about this dependency, because it is mainly tied to architecture capabilities (except in very specific cases, which would be way too complicated to explain in a Config.in comment). Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/manual/adding-packages-directory.txt14
1 files changed, 14 insertions, 0 deletions
diff --git a/docs/manual/adding-packages-directory.txt b/docs/manual/adding-packages-directory.txt
index b9596a28ca..aa9f4e81f4 100644
--- a/docs/manual/adding-packages-directory.txt
+++ b/docs/manual/adding-packages-directory.txt
@@ -279,6 +279,20 @@ use in the comment.
** Dependency symbol: +BR2_ARCH_HAS_ATOMICS+
** Comment string: no comment to be added
+* Gcc +__sync_*+ built-ins used for atomic operations. They are
+ available in variants operating on 1 byte, 2 bytes, 4 bytes and 8
+ bytes. Since different architectures support atomic operations on
+ different sizes, one dependency symbol is available for each size:
+** Dependency symbol: +BR2_TOOLCHAIN_HAS_SYNC_1+ for 1 byte,
+ +BR2_TOOLCHAIN_HAS_SYNC_2+ for 2 bytes,
+ +BR2_TOOLCHAIN_HAS_SYNC_4+ for 4 bytes, +BR2_TOOLCHAIN_HAS_SYNC_8+
+ for 8 bytes.
+** Comment string: no comment to be added
+
+* Gcc +__atomic_*+ built-ins used for atomic operations.
+** Dependency symbol: +BR2_TOOLCHAIN_HAS_ATOMIC+.
+** Comment string: no comment to be added
+
* Kernel headers
** Dependency symbol: +BR2_TOOLCHAIN_HEADERS_AT_LEAST_X_Y+, (replace
+X_Y+ with the proper version, see +toolchain/toolchain-common.in+)