diff options
Diffstat (limited to 'Documentation/cputopology.txt')
| -rw-r--r-- | Documentation/cputopology.txt | 26 |
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 |