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authorLinus Torvalds <torvalds@linux-foundation.org>2008-07-15 10:32:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-15 10:32:39 -0700
commite7849f16c13476288fe4fbd420975e8456c75aa0 (patch)
treea4f4f4a720210dd4a7879f979c9c79b6d0b75a3f /Documentation
parentaf5329cdf51cdd208a323e521faa46800a16d2ec (diff)
parent131b943ae643b1ad6febd67cdbb31d955706ecf4 (diff)
Merge branch 'core/topology' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core/topology' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: cputopology: always define CPU topology information, clean up cpu topology: always define CPU topology information
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/cputopology.txt26
1 files changed, 9 insertions, 17 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index b61cb9564023..bd699da24666 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -14,9 +14,8 @@ represent the thread siblings to cpu X in the same physical package;
To implement it in an architecture-neutral way, a new source file,
drivers/base/topology.c, is to export the 4 attributes.
-If one architecture wants to support this feature, it just needs to
-implement 4 defines, typically in file include/asm-XXX/topology.h.
-The 4 defines are:
+For an architecture to support this feature, it must define some of
+these macros in include/asm-XXX/topology.h:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
@@ -25,17 +24,10 @@ The 4 defines are:
The type of **_id is int.
The type of siblings is cpumask_t.
-To be consistent on all architectures, the 4 attributes should have
-default values if their values are unavailable. Below is the rule.
-1) physical_package_id: If cpu has no physical package id, -1 is the
-default value.
-2) core_id: If cpu doesn't support multi-core, its core id is 0.
-3) thread_siblings: Just include itself, if the cpu doesn't support
-HT/multi-thread.
-4) core_siblings: Just include itself, if the cpu doesn't support
-multi-core and HT/Multi-thread.
-
-So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
-
-If an attribute isn't defined on an architecture, it won't be exported.
-
+To be consistent on all architectures, include/linux/topology.h
+provides default definitions for any of the above macros that are
+not defined by include/asm-XXX/topology.h:
+1) physical_package_id: -1
+2) core_id: 0
+3) thread_siblings: just the given CPU
+4) core_siblings: just the given CPU