==== Keeping pointer to current thread ====

http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/intel/asm/thread.h -- thread pointer context:

extern __inline__ struct _kthread *threadp(void)
{
 	void *__value;
 
#if defined(__amd64)
 	__asm__ __volatile__(
 	    "movq %%gs:0x18,%0"		/* CPU_THREAD */
 	    : "=r" (__value));
#elif defined(__i386)
 	__asm__ __volatile__(
 	    "movl %%gs:0x10,%0"		/* CPU_THREAD */
 	    : "=r" (__value));
#else
#error	"port me"
#endif
 	return (__value);
}

(extern __inline__ explained:
http://publib.boulder.ibm.com/infocenter/compbgpl/v9v111/index.jsp?topic=/com.ibm.xlcpp9.bg.doc/language_ref/cplr243.htm --

"If you specify the __inline__ keyword, with the trailing underscores,
the compiler uses the GNU C semantics for inline functions. In
contrast to the C99 semantics, a function defined as __inline__
provides an external definition only; a function defined as static
__inline__ provides an inline definition with internal linkage (as in
C99); and a function defined as extern __inline__, when compiled with
optimization enabled, allows the co-existence of an inline and
external definition of the same function. For more information on the
GNU C implementation of inline functions, see the GCC documentation,
available at http://gcc.gnu.org/onlinedocs/." 

Why all this? See
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/intel/ia32/ml/i86_subr.s#2381
)




http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/sys/thread.h#528

extern	kthread_t	*threadp(void);	/* inline, returns thread pointer */
#define	curthread	(threadp())		/* current thread pointer */
#define	curproc		(ttoproc(curthread))	/* current process pointer */
#define	curproj		(ttoproj(curthread))	/* current project pointer */
#define	curzone		(curproc->p_zone)	/* current zone pointer */

cf: in getpid() code:

int64_t
getpid(void)
{
 	rval_t	r;
 	proc_t	*p;
 
 	p = ttoproc(curthread);
 	r.r_val1 = p->p_pid;
 	if (p->p_flag & SZONETOP)
 		r.r_val2 = curproc->p_zone->zone_zsched->p_pid;
 	else
 		r.r_val2 = p->p_ppid;
 	return (r.r_vals);
}


extern	struct _kthread	t0;		/* the scheduler thread */
extern	kmutex_t	pidlock;	/* global process lock */
 
==== Mutex Locks ====

http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/intel/ia32/ml/lock_prim.s -- x86 implementation in ASM

http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/intel/sys/mutex_impl.h -- data strcutures to implement the spin/adaptive duality

http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/os/mutex.c -- theory behind the spin/adaptive locks explained

See Chapter 17.5, especially 17.5.2 for detailed explanation: 

http://www.arl.wustl.edu/~lockwood/class/cs306/books/artofasm/Chapter_6/CH06-2.html#HEADING2-286 -- CMPXCHG explained:

cmpxchg         operand1, operand2

        if ({al/ax/eax} = operand1) then

                zero := 1               ;Set the zero flag
                operand1 := operand2

        else

                zero := 0               ;Clear the zero flag
                {al/ax/eax} := operand1

        endif


==========================================================================
Scheduler visits:

Linux:		task_struct
OpenSolaris: 	kthread_t

Per process: proc_t, kthread_t, kwlp_t (see Fig. 2.3)

Linux: 	     	lower priorities have precedence, 0 is most critical
OpenSolaris:    higher priorities have precedence, highest are most critical
		0-59 	 Time Shared, Interactive, Fixed, Fair Share Scheduler
		60-99 	 System Class
		100-159  Real-Time (note real-time higher than system threads)
		160-169  Low level Interrupts