Datasheet

Datasheet, Volume 2 525

Processor Uncore Configuration Registers
4.5.3.4 SystemSemaphore[0:1]—System Semaphore 0 Register
unCore Semaphore register is a resource shared by all threads even though it has
access and view for each one of the threads. Each one of the fields is identified to be a
shared or a dedicated element.
SystemSemaphore[0:1]
Bus: 1 Device: 11 Function: 3 Offset: A8h, ACh
Bit Attr
Reset
Value
Description
31:27 RV 0h Reserved
26:24 WO 000b
Requester Node
The requestor writes his own node id to the added into the pending vector
23:16 RV 0h Reserved
15:8 RO-V 00h
Pending Request Node
Pending request vector. Debug only usage
7:5 RV 0h Reserved
4:2 RO-V 000b
Current Node
This bit indicate the Node id of the node that currently owns the semaphore.
When the semaphore is free (Busy==0), this bit is undefined.
1RW-V 0b
Busy Acquired Release
Read - Bus status :
0 = Semaphore s currently free.
1 = Semaphore is currently busy by one of the threads.
Write - Acquire request :
0 = Release the ownership/request of the semaphore. It cause the pending bit for
the thread to be cleared.
1 = Request the ownership of the semaphore. It cause the pending bit for the
thread to be set.
uCode should poll the acquire value until ownership is granted.
0WO 0b
Acquire or Override
The bit has different meanings for read and write.
This bit has no status directly associated with it. There are different operations
associated with the read and write operations.
Write - Override acquisition :
0 = No effect
1 = Override. Take ownership of semaphore ignoring any other setting or
requests.