The DCMD_PROC_TIDSTATUS command

The DCMD_PROC_TIDSTATUS command returns a structure of type procfs_status, which is equivalent to debug_thread_t:

typedef struct _debug_thread_info64 {
    pid_t                       pid;
    pthread_t                   tid;
    uint32_t                    flags;
    uint16_t                    why;
    uint16_t                    what;
    uint64_t                    ip;
    uint64_t                    sp;
    uint64_t                    stkbase;
    uint64_t                    tls;
    uint32_t                    stksize;
    uint32_t                    tid_flags;
    uint8_t                     priority;
    uint8_t                     real_priority;
    uint8_t                     policy;
    uint8_t                     state;
    int16_t                     syscall;
    uint16_t                    last_cpu;
    uint32_t                    timeout;
    int32_t                     last_chid;
    sigset_t                    sig_blocked;
    sigset_t                    sig_pending;
    __siginfo32_t                __info32;

    // blocked thread information deleted (see next section)

    uint64_t                    start_time;
    uint64_t                    sutime;
    uint8_t                     extsched[8];
    uint64_t                    nsec_since_block;

    union {
        __siginfo32_t           info32;
        __siginfo64_t           info64;
        siginfo_t               info;
    };

    uint64_t                    reserved2[4];
} debug_thread64_t;

More information than you can shake a stick at! Here are the fields and their meanings:

pid and tid: The process ID and the thread ID.
flags: Flags indicating characteristics of the thread (see <sys/debug.h> and look for the constants beginning with _DEBUG_FLAG_).
why and what: The why indicates why the thread was stopped (see <sys/debug.h> and look for the constants beginning with _DEBUG_WHY_) and the what provides additional information for the why parameter. For _DEBUG_WHY_TERMINATED, the what variable contains the exit code value, for _DEBUG_WHY_SIGNALLED and _DEBUG_WHY_JOBCONTROL, what contains the signal number, and for _DEBUG_WHY_FAULTED, what contains the fault number (see <sys/fault.h> for the values).
ip: The current instruction pointer where this thread is executing.
sp: The current stack pointer for the thread.
stkbase and stksize: The base of the thread's stack, and the stack size.
tls: The Thread Local Storage (TLS) data area. See <sys/storage.h>.
tid_flags: See <sys/neutrino.h> constants beginning with _NTO_TF.
priority and real_priority: The priority indicates thread priority used for scheduling purposes (may be boosted), and the real_priority indicates the actual thread priority (not boosted).
policy: The scheduling policy (e.g. FIFO, Round Robin).
state: The current state of the thread (e.g., STATE_MUTEX if blocked waiting on a mutex; see <sys/states.h>).
syscall: Indicates the last system call that the thread made (see <sys/kercalls.h>).
last_cpu: The last CPU number that the thread ran on (for SMP systems).
timeout: Contains the flags parameter from the last TimerTimeout() call.
last_chid: The last channel ID that this thread MsgReceive()'d on. Used for priority boosting if a client does a MsgSend() and there are no threads in STATE_RECEIVE on the channel.
sig_blocked, sig_pending, and info: These fields all relate to signals—recall that signals have a process aspect as well as a thread aspect. The sig_blocked indicates which signals this thread has blocked. Similarly, sig_pending indicates which signals are pending on this thread. The info member carries the information for a sigwaitinfo() function.
start_time: The time, in nanoseconds since January 1, 1970, that the thread was started. Useful for detecting thread ID reuse.
sutime: Thread's system and user running times (in nanoseconds).
nsec_since_block: How long the thread has been blocked, in nanoseconds, but to millisecond resolution. This is 0 for STATE_READY or STATE_RUNNING.