Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

Export cpu topology info via sysfs. Items (attributes) are similar

to /proc/cpuinfo.

1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:

represent the physical package id of  cpu X;

2) /sys/devices/system/cpu/cpuX/topology/core_id:

represent the cpu core id to cpu X;

3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:

represent the thread siblings to cpu X in the same core;

4) /sys/devices/system/cpu/cpuX/topology/core_siblings:

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:

#define topology_physical_package_id(cpu)

#define topology_core_id(cpu)

#define topology_thread_siblings(cpu)

#define topology_core_siblings(cpu)

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.