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OpenSolaris 2009.06 - man page for p_online (opensolaris section 2)

p_online(2)				   System Calls 			      p_online(2)

NAME
       p_online - return or change processor operational status

SYNOPSIS
       #include <sys/types.h>
       #include <sys/processor.h>

       int p_online(processorid_t processorid, int flag);

DESCRIPTION
       The p_online() function changes or returns the operational status of processors. The state
       of the processor specified by the processorid argument is changed to the state represented
       by the flag argument.

       Legal values for flag are P_STATUS, P_ONLINE, P_OFFLINE, P_NOINTR, P_FAULTED, P_SPARE, and
       P_FORCED.

       When flag is P_STATUS, no processor status change occurs, but the current processor status
       is returned.

       The  P_ONLINE,  P_OFFLINE, P_NOINTR, P_FAULTED, and P_SPARE values for flag refer to valid
       processor states. The P_OFFLINE, P_SPARE,  and P_FAULTED processor states can be  combined
       with the P_FORCED flag.

       A  processor  in the P_ONLINE state is allowed to process LWPs (lightweight processes) and
       perform system activities. The processor is also interruptible by I/O devices attached  to
       the system.

       A  processor  in  the  P_OFFLINE state is not allowed to process LWPs. The processor is as
       inactive as possible. If the hardware supports such a feature, the processor is not inter-
       ruptible by attached I/O devices.

       A  processor in the P_NOINTR state is allowed to process LWPs, but it is not interruptible
       by attached I/O devices. Typically, interrupts, when they occur are routed to  other  pro-
       cessors	in  the  system.  Not  all  systems support putting a processor into the P_NOINTR
       state. It is not permitted to put all the processors of a system into the P_NOINTR  state.
       At least one processor must always be available to service system clock interrupts.

       A  processor  in  the  P_SPARE  state is not allowed to process LWPs. In many respects the
       P_SPARE state is similiar to the P_OFFLINE state, but describes a processor that is avail-
       able for reactivation by management tools without administrator intervention.

       A  processor  in  the P_FAULTED state is not allowed to process LWPs. In many respects the
       P_FAULTED state is similiar to the P_OFFLINE state, but describes  a  processor	that  has
       been diagnosed as faulty. The privileged caller can change the state of the processor from
       P_FAULTED to any of the other states, but since the processor  might  generate  additional
       errors, electing to reactivate such a processor should be carefully considered.

       Forced  processor  state transition can be requested if a new processor state is specified
       with the bitwise-inclusive OR of the special P_FORCED flag. Forcing transition of  a  pro-
       cessor  to  the	P_OFFLINE, P_SPARE, or P_FAULTED state revokes processor bindings for all
       threads that were previously bound to that processor with processor_bind(2). There  is  no
       guarantee that a forced processor state transition always succeeds.

       Processor  numbers  are integers, greater than or equal to 0, and are defined by the hard-
       ware platform.  Processor numbers are not necessarily contiguous, but  "not  too  sparse."
       Processor numbers should always be printed in decimal.

       The    maximum	 possible    processorid    value    can   be	determined   by   calling
       sysconf(_SC_CPUID_MAX). The list of valid processor numbers can be determined  by  calling
       p_online()    with    processorid   values   from   0   to   the   maximum   returned   by
       sysconf(_SC_CPUID_MAX). The EINVAL error is returned for invalid processor  numbers.   See
       EXAMPLES below.

RETURN VALUES
       On  successful  completion,  the  value	returned  is the previous state of the processor,
       P_ONLINE, P_OFFLINE,  P_NOINTR,	P_FAULTED,  P_SPARE,  or  P_POWEROFF.  Otherwise,  -1  is
       returned, the CPU state remains unchanged, and  errno is set to indicate the error.

ERRORS
       The p_online() function will fail if:

       EBUSY	  The  flag  was P_OFFLINE or P_SPARE and the specified processor is the only on-
		  line processor, there are currently  LWPs bound to the processor, or	the  pro-
		  cessor  performs  some  essential  function that cannot be performed by another
		  processor.

		  The flag was P_NOINTR and the specified processor  is  the  only  interruptible
		  processor  in  the  system,  or it handles interrupts that cannot be handled by
		  another processor.

		  The specified processor is powered off and cannot be powered	on  because  some
		  platform- specific resource is not available.

       EINVAL	  A non-existent processor ID was specified or	flag was invalid.

		  The  caller is in a non-global zone, the pools facility is active, and the pro-
		  cessor is not a member of the zone's pool's processor set.

       ENOTSUP	  The specified processor is powered off, and the platform does not support power
		  on of individual processors.

       EPERM	  The  flag  was  not  P_STATUS  and  the  {PRIV_SYS_RES_CONFIG} privilege is not
		  asserted in the effective set of the calling process.

EXAMPLES
       Example 1 List the legal processor numbers.

       The following code sample will list the legal processor numbers:

	 #include <sys/unistd.h>
	 #include <sys/processor.h>
	 #include <sys/types.h>
	 #include <stdio.h>
	 #include <unistd.h>
	 #include <errno.h>

	 int
	 main()
	 {
		 processorid_t i, cpuid_max;
		 cpuid_max = sysconf(_SC_CPUID_MAX);
		 for (i = 0; i <= cpuid_max; i++) {
		       if (p_online(i, P_STATUS) != -1)
				 printf("processor %d present\n", i);
		 }
		 return(0);
	 }

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       pooladm(1M), psradm(1M), psrinfo(1M), zoneadm(1M),  processor_bind(2),  processor_info(2),
       pset_create(2), sysconf(3C), attributes(5), privileges(5)

SunOS 5.11				   11 Jan 2009				      p_online(2)


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