ntp_loopfilter.c revision 293896
1/* 2 * ntp_loopfilter.c - implements the NTP loop filter algorithm 3 * 4 * ATTENTION: Get approval from Dave Mills on all changes to this file! 5 * 6 */ 7#ifdef HAVE_CONFIG_H 8# include <config.h> 9#endif 10 11#ifdef USE_SNPRINTB 12# include <util.h> 13#endif 14#include "ntpd.h" 15#include "ntp_io.h" 16#include "ntp_unixtime.h" 17#include "ntp_stdlib.h" 18 19#include <limits.h> 20#include <stdio.h> 21#include <ctype.h> 22 23#include <signal.h> 24#include <setjmp.h> 25 26#ifdef KERNEL_PLL 27#include "ntp_syscall.h" 28#endif /* KERNEL_PLL */ 29 30/* 31 * This is an implementation of the clock discipline algorithm described 32 * in UDel TR 97-4-3, as amended. It operates as an adaptive parameter, 33 * hybrid phase/frequency-lock loop. A number of sanity checks are 34 * included to protect against timewarps, timespikes and general mayhem. 35 * All units are in s and s/s, unless noted otherwise. 36 */ 37#define CLOCK_MAX .128 /* default step threshold (s) */ 38#define CLOCK_MINSTEP 300. /* default stepout threshold (s) */ 39#define CLOCK_PANIC 1000. /* default panic threshold (s) */ 40#define CLOCK_PHI 15e-6 /* max frequency error (s/s) */ 41#define CLOCK_PLL 16. /* PLL loop gain (log2) */ 42#define CLOCK_AVG 8. /* parameter averaging constant */ 43#define CLOCK_FLL .25 /* FLL loop gain */ 44#define CLOCK_FLOOR .0005 /* startup offset floor (s) */ 45#define CLOCK_ALLAN 11 /* Allan intercept (log2 s) */ 46#define CLOCK_LIMIT 30 /* poll-adjust threshold */ 47#define CLOCK_PGATE 4. /* poll-adjust gate */ 48#define PPS_MAXAGE 120 /* kernel pps signal timeout (s) */ 49#define FREQTOD(x) ((x) / 65536e6) /* NTP to double */ 50#define DTOFREQ(x) ((int32)((x) * 65536e6)) /* double to NTP */ 51 52/* 53 * Clock discipline state machine. This is used to control the 54 * synchronization behavior during initialization and following a 55 * timewarp. 56 * 57 * State < step > step Comments 58 * ======================================================== 59 * NSET FREQ step, FREQ freq not set 60 * 61 * FSET SYNC step, SYNC freq set 62 * 63 * FREQ if (mu < 900) if (mu < 900) set freq direct 64 * ignore ignore 65 * else else 66 * freq, SYNC freq, step, SYNC 67 * 68 * SYNC SYNC SPIK, ignore adjust phase/freq 69 * 70 * SPIK SYNC if (mu < 900) adjust phase/freq 71 * ignore 72 * step, SYNC 73 */ 74/* 75 * Kernel PLL/PPS state machine. This is used with the kernel PLL 76 * modifications described in the documentation. 77 * 78 * If kernel support for the ntp_adjtime() system call is available, the 79 * ntp_control flag is set. The ntp_enable and kern_enable flags can be 80 * set at configuration time or run time using ntpdc. If ntp_enable is 81 * false, the discipline loop is unlocked and no corrections of any kind 82 * are made. If both ntp_control and kern_enable are set, the kernel 83 * support is used as described above; if false, the kernel is bypassed 84 * entirely and the daemon discipline used instead. 85 * 86 * There have been three versions of the kernel discipline code. The 87 * first (microkernel) now in Solaris discipilnes the microseconds. The 88 * second and third (nanokernel) disciplines the clock in nanoseconds. 89 * These versions are identifed if the symbol STA_PLL is present in the 90 * header file /usr/include/sys/timex.h. The third and current version 91 * includes TAI offset and is identified by the symbol NTP_API with 92 * value 4. 93 * 94 * Each PPS time/frequency discipline can be enabled by the atom driver 95 * or another driver. If enabled, the STA_PPSTIME and STA_FREQ bits are 96 * set in the kernel status word; otherwise, these bits are cleared. 97 * These bits are also cleard if the kernel reports an error. 98 * 99 * If an external clock is present, the clock driver sets STA_CLK in the 100 * status word. When the local clock driver sees this bit, it updates 101 * via this routine, which then calls ntp_adjtime() with the STA_PLL bit 102 * set to zero, in which case the system clock is not adjusted. This is 103 * also a signal for the external clock driver to discipline the system 104 * clock. Unless specified otherwise, all times are in seconds. 105 */ 106/* 107 * Program variables that can be tinkered. 108 */ 109double clock_max_back = CLOCK_MAX; /* step threshold */ 110double clock_max_fwd = CLOCK_MAX; /* step threshold */ 111double clock_minstep = CLOCK_MINSTEP; /* stepout threshold */ 112double clock_panic = CLOCK_PANIC; /* panic threshold */ 113double clock_phi = CLOCK_PHI; /* dispersion rate (s/s) */ 114u_char allan_xpt = CLOCK_ALLAN; /* Allan intercept (log2 s) */ 115 116/* 117 * Program variables 118 */ 119static double clock_offset; /* offset */ 120double clock_jitter; /* offset jitter */ 121double drift_comp; /* frequency (s/s) */ 122static double init_drift_comp; /* initial frequency (PPM) */ 123double clock_stability; /* frequency stability (wander) (s/s) */ 124double clock_codec; /* audio codec frequency (samples/s) */ 125static u_long clock_epoch; /* last update */ 126u_int sys_tai; /* TAI offset from UTC */ 127static int loop_started; /* TRUE after LOOP_DRIFTINIT */ 128static void rstclock (int, double); /* transition function */ 129static double direct_freq(double); /* direct set frequency */ 130static void set_freq(double); /* set frequency */ 131#ifndef PATH_MAX 132# define PATH_MAX MAX_PATH 133#endif 134static char relative_path[PATH_MAX + 1]; /* relative path per recursive make */ 135static char *this_file = NULL; 136 137#ifdef KERNEL_PLL 138static struct timex ntv; /* ntp_adjtime() parameters */ 139int pll_status; /* last kernel status bits */ 140#if defined(STA_NANO) && NTP_API == 4 141static u_int loop_tai; /* last TAI offset */ 142#endif /* STA_NANO */ 143static void start_kern_loop(void); 144static void stop_kern_loop(void); 145#endif /* KERNEL_PLL */ 146 147/* 148 * Clock state machine control flags 149 */ 150int ntp_enable = TRUE; /* clock discipline enabled */ 151int pll_control; /* kernel support available */ 152int kern_enable = TRUE; /* kernel support enabled */ 153int hardpps_enable; /* kernel PPS discipline enabled */ 154int ext_enable; /* external clock enabled */ 155int pps_stratum; /* pps stratum */ 156int kernel_status; /* from ntp_adjtime */ 157int force_step_once = FALSE; /* always step time once at startup (-G) */ 158int mode_ntpdate = FALSE; /* exit on first clock set (-q) */ 159int freq_cnt; /* initial frequency clamp */ 160int freq_set; /* initial set frequency switch */ 161 162/* 163 * Clock state machine variables 164 */ 165int state = 0; /* clock discipline state */ 166u_char sys_poll; /* time constant/poll (log2 s) */ 167int tc_counter; /* jiggle counter */ 168double last_offset; /* last offset (s) */ 169 170/* 171 * Huff-n'-puff filter variables 172 */ 173static double *sys_huffpuff; /* huff-n'-puff filter */ 174static int sys_hufflen; /* huff-n'-puff filter stages */ 175static int sys_huffptr; /* huff-n'-puff filter pointer */ 176static double sys_mindly; /* huff-n'-puff filter min delay */ 177 178#if defined(KERNEL_PLL) 179/* Emacs cc-mode goes nuts if we split the next line... */ 180#define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | \ 181 MOD_STATUS | MOD_TIMECONST) 182#ifdef SIGSYS 183static void pll_trap (int); /* configuration trap */ 184static struct sigaction sigsys; /* current sigaction status */ 185static struct sigaction newsigsys; /* new sigaction status */ 186static sigjmp_buf env; /* environment var. for pll_trap() */ 187#endif /* SIGSYS */ 188#endif /* KERNEL_PLL */ 189 190static void 191sync_status(const char *what, int ostatus, int nstatus) 192{ 193 char obuf[256], nbuf[256], tbuf[1024]; 194#if defined(USE_SNPRINTB) && defined (STA_FMT) 195 snprintb(obuf, sizeof(obuf), STA_FMT, ostatus); 196 snprintb(nbuf, sizeof(nbuf), STA_FMT, nstatus); 197#else 198 snprintf(obuf, sizeof(obuf), "%04x", ostatus); 199 snprintf(nbuf, sizeof(nbuf), "%04x", nstatus); 200#endif 201 snprintf(tbuf, sizeof(tbuf), "%s status: %s -> %s", what, obuf, nbuf); 202 report_event(EVNT_KERN, NULL, tbuf); 203} 204 205/* 206 * file_name - return pointer to non-relative portion of this C file pathname 207 */ 208static char *file_name(void) 209{ 210 if (this_file == NULL) { 211 (void)strncpy(relative_path, __FILE__, PATH_MAX); 212 for (this_file=relative_path; 213 *this_file && ! isalnum((unsigned char)*this_file); 214 this_file++) ; 215 } 216 return this_file; 217} 218 219/* 220 * init_loopfilter - initialize loop filter data 221 */ 222void 223init_loopfilter(void) 224{ 225 /* 226 * Initialize state variables. 227 */ 228 sys_poll = ntp_minpoll; 229 clock_jitter = LOGTOD(sys_precision); 230 freq_cnt = (int)clock_minstep; 231} 232 233#ifdef KERNEL_PLL 234/* 235 * ntp_adjtime_error_handler - process errors from ntp_adjtime 236 */ 237static void 238ntp_adjtime_error_handler( 239 const char *caller, /* name of calling function */ 240 struct timex *ptimex, /* pointer to struct timex */ 241 int ret, /* return value from ntp_adjtime */ 242 int saved_errno, /* value of errno when ntp_adjtime returned */ 243 int pps_call, /* ntp_adjtime call was PPS-related */ 244 int tai_call, /* ntp_adjtime call was TAI-related */ 245 int line /* line number of ntp_adjtime call */ 246 ) 247{ 248 char des[1024] = ""; /* Decoded Error Status */ 249 250 switch (ret) { 251 case -1: 252 switch (saved_errno) { 253 case EFAULT: 254 msyslog(LOG_ERR, "%s: %s line %d: invalid struct timex pointer: 0x%lx", 255 caller, file_name(), line, 256 (long)((void *)ptimex) 257 ); 258 break; 259 case EINVAL: 260 msyslog(LOG_ERR, "%s: %s line %d: invalid struct timex \"constant\" element value: %ld", 261 caller, file_name(), line, 262 (long)(ptimex->constant) 263 ); 264 break; 265 case EPERM: 266 if (tai_call) { 267 errno = saved_errno; 268 msyslog(LOG_ERR, 269 "%s: ntp_adjtime(TAI) failed: %m", 270 caller); 271 } 272 errno = saved_errno; 273 msyslog(LOG_ERR, "%s: %s line %d: ntp_adjtime: %m", 274 caller, file_name(), line 275 ); 276 break; 277 default: 278 msyslog(LOG_NOTICE, "%s: %s line %d: unhandled errno value %d after failed ntp_adjtime call", 279 caller, file_name(), line, 280 saved_errno 281 ); 282 break; 283 } 284 break; 285#ifdef TIME_OK 286 case TIME_OK: /* 0: synchronized, no leap second warning */ 287 /* msyslog(LOG_INFO, "kernel reports time is synchronized normally"); */ 288 break; 289#else 290# warning TIME_OK is not defined 291#endif 292#ifdef TIME_INS 293 case TIME_INS: /* 1: positive leap second warning */ 294 msyslog(LOG_INFO, "kernel reports leap second insertion scheduled"); 295 break; 296#else 297# warning TIME_INS is not defined 298#endif 299#ifdef TIME_DEL 300 case TIME_DEL: /* 2: negative leap second warning */ 301 msyslog(LOG_INFO, "kernel reports leap second deletion scheduled"); 302 break; 303#else 304# warning TIME_DEL is not defined 305#endif 306#ifdef TIME_OOP 307 case TIME_OOP: /* 3: leap second in progress */ 308 msyslog(LOG_INFO, "kernel reports leap second in progress"); 309 break; 310#else 311# warning TIME_OOP is not defined 312#endif 313#ifdef TIME_WAIT 314 case TIME_WAIT: /* 4: leap second has occured */ 315 msyslog(LOG_INFO, "kernel reports leap second has occurred"); 316 break; 317#else 318# warning TIME_WAIT is not defined 319#endif 320#ifdef TIME_ERROR 321#if 0 322 323from the reference implementation of ntp_gettime(): 324 325 // Hardware or software error 326 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) 327 328 /* 329 * PPS signal lost when either time or frequency synchronization 330 * requested 331 */ 332 || (time_status & (STA_PPSFREQ | STA_PPSTIME) 333 && !(time_status & STA_PPSSIGNAL)) 334 335 /* 336 * PPS jitter exceeded when time synchronization requested 337 */ 338 || (time_status & STA_PPSTIME && 339 time_status & STA_PPSJITTER) 340 341 /* 342 * PPS wander exceeded or calibration error when frequency 343 * synchronization requested 344 */ 345 || (time_status & STA_PPSFREQ && 346 time_status & (STA_PPSWANDER | STA_PPSERROR))) 347 return (TIME_ERROR); 348 349or, from ntp_adjtime(): 350 351 if ( (time_status & (STA_UNSYNC | STA_CLOCKERR)) 352 || (time_status & (STA_PPSFREQ | STA_PPSTIME) 353 && !(time_status & STA_PPSSIGNAL)) 354 || (time_status & STA_PPSTIME 355 && time_status & STA_PPSJITTER) 356 || (time_status & STA_PPSFREQ 357 && time_status & (STA_PPSWANDER | STA_PPSERROR)) 358 ) 359 return (TIME_ERROR); 360#endif 361 362 case TIME_ERROR: /* 5: unsynchronized, or loss of synchronization */ 363 /* error (see status word) */ 364 365 if (ptimex->status & STA_UNSYNC) 366 snprintf(des, sizeof(des), "%s%sClock Unsynchronized", 367 des, (*des) ? "; " : ""); 368 369 if (ptimex->status & STA_CLOCKERR) 370 snprintf(des, sizeof(des), "%s%sClock Error", 371 des, (*des) ? "; " : ""); 372 373 if (!(ptimex->status & STA_PPSSIGNAL) 374 && ptimex->status & STA_PPSFREQ) 375 snprintf(des, sizeof(des), "%s%sPPS Frequency Sync wanted but no PPS", 376 des, (*des) ? "; " : ""); 377 378 if (!(ptimex->status & STA_PPSSIGNAL) 379 && ptimex->status & STA_PPSTIME) 380 snprintf(des, sizeof(des), "%s%sPPS Time Sync wanted but no PPS signal", 381 des, (*des) ? "; " : ""); 382 383 if ( ptimex->status & STA_PPSTIME 384 && ptimex->status & STA_PPSJITTER) 385 snprintf(des, sizeof(des), "%s%sPPS Time Sync wanted but PPS Jitter exceeded", 386 des, (*des) ? "; " : ""); 387 388 if ( ptimex->status & STA_PPSFREQ 389 && ptimex->status & STA_PPSWANDER) 390 snprintf(des, sizeof(des), "%s%sPPS Frequency Sync wanted but PPS Wander exceeded", 391 des, (*des) ? "; " : ""); 392 393 if ( ptimex->status & STA_PPSFREQ 394 && ptimex->status & STA_PPSERROR) 395 snprintf(des, sizeof(des), "%s%sPPS Frequency Sync wanted but Calibration error detected", 396 des, (*des) ? "; " : ""); 397 398 if (pps_call && !(ptimex->status & STA_PPSSIGNAL)) 399 report_event(EVNT_KERN, NULL, 400 "no PPS signal"); 401 DPRINTF(1, ("kernel loop status %#x (%s)\n", 402 ptimex->status, des)); 403 /* 404 * This code may be returned when ntp_adjtime() has just 405 * been called for the first time, quite a while after 406 * startup, when ntpd just starts to discipline the kernel 407 * time. In this case the occurrence of this message 408 * can be pretty confusing. 409 * 410 * HMS: How about a message when we begin kernel processing: 411 * Determining kernel clock state... 412 * so an initial TIME_ERROR message is less confising, 413 * or skipping the first message (ugh), 414 * or ??? 415 * msyslog(LOG_INFO, "kernel reports time synchronization lost"); 416 */ 417 msyslog(LOG_INFO, "kernel reports TIME_ERROR: %#x: %s", 418 ptimex->status, des); 419 break; 420#else 421# warning TIME_ERROR is not defined 422#endif 423 default: 424 msyslog(LOG_NOTICE, "%s: %s line %d: unhandled return value %d from ntp_adjtime() in %s at line %d", 425 caller, file_name(), line, 426 ret, 427 __func__, __LINE__ 428 ); 429 break; 430 } 431 return; 432} 433#endif 434 435/* 436 * local_clock - the NTP logical clock loop filter. 437 * 438 * Return codes: 439 * -1 update ignored: exceeds panic threshold 440 * 0 update ignored: popcorn or exceeds step threshold 441 * 1 clock was slewed 442 * 2 clock was stepped 443 * 444 * LOCKCLOCK: The only thing this routine does is set the 445 * sys_rootdisp variable equal to the peer dispersion. 446 */ 447int 448local_clock( 449 struct peer *peer, /* synch source peer structure */ 450 double fp_offset /* clock offset (s) */ 451 ) 452{ 453 int rval; /* return code */ 454 int osys_poll; /* old system poll */ 455 int ntp_adj_ret; /* returned by ntp_adjtime */ 456 double mu; /* interval since last update */ 457 double clock_frequency; /* clock frequency */ 458 double dtemp, etemp; /* double temps */ 459 char tbuf[80]; /* report buffer */ 460 461 (void)ntp_adj_ret; /* not always used below... */ 462 /* 463 * If the loop is opened or the NIST LOCKCLOCK is in use, 464 * monitor and record the offsets anyway in order to determine 465 * the open-loop response and then go home. 466 */ 467#ifndef LOCKCLOCK 468 if (!ntp_enable) 469#endif /* not LOCKCLOCK */ 470 { 471 record_loop_stats(fp_offset, drift_comp, clock_jitter, 472 clock_stability, sys_poll); 473 return (0); 474 } 475 476#ifndef LOCKCLOCK 477 /* 478 * If the clock is way off, panic is declared. The clock_panic 479 * defaults to 1000 s; if set to zero, the panic will never 480 * occur. The allow_panic defaults to FALSE, so the first panic 481 * will exit. It can be set TRUE by a command line option, in 482 * which case the clock will be set anyway and time marches on. 483 * But, allow_panic will be set FALSE when the update is less 484 * than the step threshold; so, subsequent panics will exit. 485 */ 486 if (fabs(fp_offset) > clock_panic && clock_panic > 0 && 487 !allow_panic) { 488 snprintf(tbuf, sizeof(tbuf), 489 "%+.0f s; set clock manually within %.0f s.", 490 fp_offset, clock_panic); 491 report_event(EVNT_SYSFAULT, NULL, tbuf); 492 return (-1); 493 } 494 495 allow_panic = FALSE; 496 497 /* 498 * This section simulates ntpdate. If the offset exceeds the 499 * step threshold (128 ms), step the clock to that time and 500 * exit. Otherwise, slew the clock to that time and exit. Note 501 * that the slew will persist and eventually complete beyond the 502 * life of this program. Note that while ntpdate is active, the 503 * terminal does not detach, so the termination message prints 504 * directly to the terminal. 505 */ 506 if (mode_ntpdate) { 507 if ( ( fp_offset > clock_max_fwd && clock_max_fwd > 0) 508 || (-fp_offset > clock_max_back && clock_max_back > 0)) { 509 step_systime(fp_offset); 510 msyslog(LOG_NOTICE, "ntpd: time set %+.6f s", 511 fp_offset); 512 printf("ntpd: time set %+.6fs\n", fp_offset); 513 } else { 514 adj_systime(fp_offset); 515 msyslog(LOG_NOTICE, "ntpd: time slew %+.6f s", 516 fp_offset); 517 printf("ntpd: time slew %+.6fs\n", fp_offset); 518 } 519 record_loop_stats(fp_offset, drift_comp, clock_jitter, 520 clock_stability, sys_poll); 521 exit (0); 522 } 523 524 /* 525 * The huff-n'-puff filter finds the lowest delay in the recent 526 * interval. This is used to correct the offset by one-half the 527 * difference between the sample delay and minimum delay. This 528 * is most effective if the delays are highly assymetric and 529 * clockhopping is avoided and the clock frequency wander is 530 * relatively small. 531 */ 532 if (sys_huffpuff != NULL) { 533 if (peer->delay < sys_huffpuff[sys_huffptr]) 534 sys_huffpuff[sys_huffptr] = peer->delay; 535 if (peer->delay < sys_mindly) 536 sys_mindly = peer->delay; 537 if (fp_offset > 0) 538 dtemp = -(peer->delay - sys_mindly) / 2; 539 else 540 dtemp = (peer->delay - sys_mindly) / 2; 541 fp_offset += dtemp; 542 DPRINTF(1, ("local_clock: size %d mindly %.6f huffpuff %.6f\n", 543 sys_hufflen, sys_mindly, dtemp)); 544 } 545 546 /* 547 * Clock state machine transition function which defines how the 548 * system reacts to large phase and frequency excursion. There 549 * are two main regimes: when the offset exceeds the step 550 * threshold (128 ms) and when it does not. Under certain 551 * conditions updates are suspended until the stepout theshold 552 * (900 s) is exceeded. See the documentation on how these 553 * thresholds interact with commands and command line options. 554 * 555 * Note the kernel is disabled if step is disabled or greater 556 * than 0.5 s or in ntpdate mode. 557 */ 558 osys_poll = sys_poll; 559 if (sys_poll < peer->minpoll) 560 sys_poll = peer->minpoll; 561 if (sys_poll > peer->maxpoll) 562 sys_poll = peer->maxpoll; 563 mu = current_time - clock_epoch; 564 clock_frequency = drift_comp; 565 rval = 1; 566 if ( ( fp_offset > clock_max_fwd && clock_max_fwd > 0) 567 || (-fp_offset > clock_max_back && clock_max_back > 0) 568 || force_step_once ) { 569 if (force_step_once) { 570 force_step_once = FALSE; /* we want this only once after startup */ 571 msyslog(LOG_NOTICE, "Doing intital time step" ); 572 } 573 574 switch (state) { 575 576 /* 577 * In SYNC state we ignore the first outlier and switch 578 * to SPIK state. 579 */ 580 case EVNT_SYNC: 581 snprintf(tbuf, sizeof(tbuf), "%+.6f s", 582 fp_offset); 583 report_event(EVNT_SPIK, NULL, tbuf); 584 state = EVNT_SPIK; 585 return (0); 586 587 /* 588 * In FREQ state we ignore outliers and inlyers. At the 589 * first outlier after the stepout threshold, compute 590 * the apparent frequency correction and step the phase. 591 */ 592 case EVNT_FREQ: 593 if (mu < clock_minstep) 594 return (0); 595 596 clock_frequency = direct_freq(fp_offset); 597 598 /* fall through to EVNT_SPIK */ 599 600 /* 601 * In SPIK state we ignore succeeding outliers until 602 * either an inlyer is found or the stepout threshold is 603 * exceeded. 604 */ 605 case EVNT_SPIK: 606 if (mu < clock_minstep) 607 return (0); 608 609 /* fall through to default */ 610 611 /* 612 * We get here by default in NSET and FSET states and 613 * from above in FREQ or SPIK states. 614 * 615 * In NSET state an initial frequency correction is not 616 * available, usually because the frequency file has not 617 * yet been written. Since the time is outside the step 618 * threshold, the clock is stepped. The frequency will 619 * be set directly following the stepout interval. 620 * 621 * In FSET state the initial frequency has been set from 622 * the frequency file. Since the time is outside the 623 * step threshold, the clock is stepped immediately, 624 * rather than after the stepout interval. Guys get 625 * nervous if it takes 15 minutes to set the clock for 626 * the first time. 627 * 628 * In FREQ and SPIK states the stepout threshold has 629 * expired and the phase is still above the step 630 * threshold. Note that a single spike greater than the 631 * step threshold is always suppressed, even with a 632 * long time constant. 633 */ 634 default: 635 snprintf(tbuf, sizeof(tbuf), "%+.6f s", 636 fp_offset); 637 report_event(EVNT_CLOCKRESET, NULL, tbuf); 638 step_systime(fp_offset); 639 reinit_timer(); 640 tc_counter = 0; 641 clock_jitter = LOGTOD(sys_precision); 642 rval = 2; 643 if (state == EVNT_NSET) { 644 rstclock(EVNT_FREQ, 0); 645 return (rval); 646 } 647 break; 648 } 649 rstclock(EVNT_SYNC, 0); 650 } else { 651 /* 652 * The offset is less than the step threshold. Calculate 653 * the jitter as the exponentially weighted offset 654 * differences. 655 */ 656 etemp = SQUARE(clock_jitter); 657 dtemp = SQUARE(max(fabs(fp_offset - last_offset), 658 LOGTOD(sys_precision))); 659 clock_jitter = SQRT(etemp + (dtemp - etemp) / 660 CLOCK_AVG); 661 switch (state) { 662 663 /* 664 * In NSET state this is the first update received and 665 * the frequency has not been initialized. Adjust the 666 * phase, but do not adjust the frequency until after 667 * the stepout threshold. 668 */ 669 case EVNT_NSET: 670 adj_systime(fp_offset); 671 rstclock(EVNT_FREQ, fp_offset); 672 break; 673 674 /* 675 * In FREQ state ignore updates until the stepout 676 * threshold. After that, compute the new frequency, but 677 * do not adjust the frequency until the holdoff counter 678 * decrements to zero. 679 */ 680 case EVNT_FREQ: 681 if (mu < clock_minstep) 682 return (0); 683 684 clock_frequency = direct_freq(fp_offset); 685 /* fall through */ 686 687 /* 688 * We get here by default in FSET, SPIK and SYNC states. 689 * Here compute the frequency update due to PLL and FLL 690 * contributions. Note, we avoid frequency discipline at 691 * startup until the initial transient has subsided. 692 */ 693 default: 694 if (freq_cnt == 0) { 695 696 /* 697 * The FLL and PLL frequency gain constants 698 * depend on the time constant and Allan 699 * intercept. The PLL is always used, but 700 * becomes ineffective above the Allan intercept 701 * where the FLL becomes effective. 702 */ 703 if (sys_poll >= allan_xpt) 704 clock_frequency += (fp_offset - 705 clock_offset) / max(ULOGTOD(sys_poll), 706 mu) * CLOCK_FLL; 707 708 /* 709 * The PLL frequency gain (numerator) depends on 710 * the minimum of the update interval and Allan 711 * intercept. This reduces the PLL gain when the 712 * FLL becomes effective. 713 */ 714 etemp = min(ULOGTOD(allan_xpt), mu); 715 dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll); 716 clock_frequency += fp_offset * etemp / (dtemp * 717 dtemp); 718 } 719 rstclock(EVNT_SYNC, fp_offset); 720 if (fabs(fp_offset) < CLOCK_FLOOR) 721 freq_cnt = 0; 722 break; 723 } 724 } 725 726#ifdef KERNEL_PLL 727 /* 728 * This code segment works when clock adjustments are made using 729 * precision time kernel support and the ntp_adjtime() system 730 * call. This support is available in Solaris 2.6 and later, 731 * Digital Unix 4.0 and later, FreeBSD, Linux and specially 732 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the 733 * DECstation 5000/240 and Alpha AXP, additional kernel 734 * modifications provide a true microsecond clock and nanosecond 735 * clock, respectively. 736 * 737 * Important note: The kernel discipline is used only if the 738 * step threshold is less than 0.5 s, as anything higher can 739 * lead to overflow problems. This might occur if some misguided 740 * lad set the step threshold to something ridiculous. 741 */ 742 if (pll_control && kern_enable && freq_cnt == 0) { 743 744 /* 745 * We initialize the structure for the ntp_adjtime() 746 * system call. We have to convert everything to 747 * microseconds or nanoseconds first. Do not update the 748 * system variables if the ext_enable flag is set. In 749 * this case, the external clock driver will update the 750 * variables, which will be read later by the local 751 * clock driver. Afterwards, remember the time and 752 * frequency offsets for jitter and stability values and 753 * to update the frequency file. 754 */ 755 ZERO(ntv); 756 if (ext_enable) { 757 ntv.modes = MOD_STATUS; 758 } else { 759#ifdef STA_NANO 760 ntv.modes = MOD_BITS | MOD_NANO; 761#else /* STA_NANO */ 762 ntv.modes = MOD_BITS; 763#endif /* STA_NANO */ 764 if (clock_offset < 0) 765 dtemp = -.5; 766 else 767 dtemp = .5; 768#ifdef STA_NANO 769 ntv.offset = (int32)(clock_offset * 1e9 + 770 dtemp); 771 ntv.constant = sys_poll; 772#else /* STA_NANO */ 773 ntv.offset = (int32)(clock_offset * 1e6 + 774 dtemp); 775 ntv.constant = sys_poll - 4; 776#endif /* STA_NANO */ 777 if (ntv.constant < 0) 778 ntv.constant = 0; 779 780 ntv.esterror = (u_int32)(clock_jitter * 1e6); 781 ntv.maxerror = (u_int32)((sys_rootdelay / 2 + 782 sys_rootdisp) * 1e6); 783 ntv.status = STA_PLL; 784 785 /* 786 * Enable/disable the PPS if requested. 787 */ 788 if (hardpps_enable) { 789 ntv.status |= (STA_PPSTIME | STA_PPSFREQ); 790 if (!(pll_status & STA_PPSTIME)) 791 sync_status("PPS enabled", 792 pll_status, 793 ntv.status); 794 } else { 795 ntv.status &= ~(STA_PPSTIME | STA_PPSFREQ); 796 if (pll_status & STA_PPSTIME) 797 sync_status("PPS disabled", 798 pll_status, 799 ntv.status); 800 } 801 if (sys_leap == LEAP_ADDSECOND) 802 ntv.status |= STA_INS; 803 else if (sys_leap == LEAP_DELSECOND) 804 ntv.status |= STA_DEL; 805 } 806 807 /* 808 * Pass the stuff to the kernel. If it squeals, turn off 809 * the pps. In any case, fetch the kernel offset, 810 * frequency and jitter. 811 */ 812 ntp_adj_ret = ntp_adjtime(&ntv); 813 /* 814 * A squeal is a return status < 0, or a state change. 815 */ 816 if ((0 > ntp_adj_ret) || (ntp_adj_ret != kernel_status)) { 817 kernel_status = ntp_adj_ret; 818 ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, hardpps_enable, 0, __LINE__ - 1); 819 } 820 pll_status = ntv.status; 821#ifdef STA_NANO 822 clock_offset = ntv.offset / 1e9; 823#else /* STA_NANO */ 824 clock_offset = ntv.offset / 1e6; 825#endif /* STA_NANO */ 826 clock_frequency = FREQTOD(ntv.freq); 827 828 /* 829 * If the kernel PPS is lit, monitor its performance. 830 */ 831 if (ntv.status & STA_PPSTIME) { 832#ifdef STA_NANO 833 clock_jitter = ntv.jitter / 1e9; 834#else /* STA_NANO */ 835 clock_jitter = ntv.jitter / 1e6; 836#endif /* STA_NANO */ 837 } 838 839#if defined(STA_NANO) && NTP_API == 4 840 /* 841 * If the TAI changes, update the kernel TAI. 842 */ 843 if (loop_tai != sys_tai) { 844 loop_tai = sys_tai; 845 ntv.modes = MOD_TAI; 846 ntv.constant = sys_tai; 847 if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) { 848 ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 1, __LINE__ - 1); 849 } 850 } 851#endif /* STA_NANO */ 852 } 853#endif /* KERNEL_PLL */ 854 855 /* 856 * Clamp the frequency within the tolerance range and calculate 857 * the frequency difference since the last update. 858 */ 859 if (fabs(clock_frequency) > NTP_MAXFREQ) 860 msyslog(LOG_NOTICE, 861 "frequency error %.0f PPM exceeds tolerance %.0f PPM", 862 clock_frequency * 1e6, NTP_MAXFREQ * 1e6); 863 dtemp = SQUARE(clock_frequency - drift_comp); 864 if (clock_frequency > NTP_MAXFREQ) 865 drift_comp = NTP_MAXFREQ; 866 else if (clock_frequency < -NTP_MAXFREQ) 867 drift_comp = -NTP_MAXFREQ; 868 else 869 drift_comp = clock_frequency; 870 871 /* 872 * Calculate the wander as the exponentially weighted RMS 873 * frequency differences. Record the change for the frequency 874 * file update. 875 */ 876 etemp = SQUARE(clock_stability); 877 clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG); 878 879 /* 880 * Here we adjust the time constant by comparing the current 881 * offset with the clock jitter. If the offset is less than the 882 * clock jitter times a constant, then the averaging interval is 883 * increased, otherwise it is decreased. A bit of hysteresis 884 * helps calm the dance. Works best using burst mode. Don't 885 * fiddle with the poll during the startup clamp period. 886 */ 887 if (freq_cnt > 0) { 888 tc_counter = 0; 889 } else if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) { 890 tc_counter += sys_poll; 891 if (tc_counter > CLOCK_LIMIT) { 892 tc_counter = CLOCK_LIMIT; 893 if (sys_poll < peer->maxpoll) { 894 tc_counter = 0; 895 sys_poll++; 896 } 897 } 898 } else { 899 tc_counter -= sys_poll << 1; 900 if (tc_counter < -CLOCK_LIMIT) { 901 tc_counter = -CLOCK_LIMIT; 902 if (sys_poll > peer->minpoll) { 903 tc_counter = 0; 904 sys_poll--; 905 } 906 } 907 } 908 909 /* 910 * If the time constant has changed, update the poll variables. 911 */ 912 if (osys_poll != sys_poll) 913 poll_update(peer, sys_poll); 914 915 /* 916 * Yibbidy, yibbbidy, yibbidy; that'h all folks. 917 */ 918 record_loop_stats(clock_offset, drift_comp, clock_jitter, 919 clock_stability, sys_poll); 920 DPRINTF(1, ("local_clock: offset %.9f jit %.9f freq %.3f stab %.3f poll %d\n", 921 clock_offset, clock_jitter, drift_comp * 1e6, 922 clock_stability * 1e6, sys_poll)); 923 return (rval); 924#endif /* not LOCKCLOCK */ 925} 926 927 928/* 929 * adj_host_clock - Called once every second to update the local clock. 930 * 931 * LOCKCLOCK: The only thing this routine does is increment the 932 * sys_rootdisp variable. 933 */ 934void 935adj_host_clock( 936 void 937 ) 938{ 939 double offset_adj; 940 double freq_adj; 941 942 /* 943 * Update the dispersion since the last update. In contrast to 944 * NTPv3, NTPv4 does not declare unsynchronized after one day, 945 * since the dispersion check serves this function. Also, 946 * since the poll interval can exceed one day, the old test 947 * would be counterproductive. During the startup clamp period, the 948 * time constant is clamped at 2. 949 */ 950 sys_rootdisp += clock_phi; 951#ifndef LOCKCLOCK 952 if (!ntp_enable || mode_ntpdate) 953 return; 954 /* 955 * Determine the phase adjustment. The gain factor (denominator) 956 * increases with poll interval, so is dominated by the FLL 957 * above the Allan intercept. Note the reduced time constant at 958 * startup. 959 */ 960 if (state != EVNT_SYNC) { 961 offset_adj = 0.; 962 } else if (freq_cnt > 0) { 963 offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(1)); 964 freq_cnt--; 965#ifdef KERNEL_PLL 966 } else if (pll_control && kern_enable) { 967 offset_adj = 0.; 968#endif /* KERNEL_PLL */ 969 } else { 970 offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll)); 971 } 972 973 /* 974 * If the kernel discipline is enabled the frequency correction 975 * drift_comp has already been engaged via ntp_adjtime() in 976 * set_freq(). Otherwise it is a component of the adj_systime() 977 * offset. 978 */ 979#ifdef KERNEL_PLL 980 if (pll_control && kern_enable) 981 freq_adj = 0.; 982 else 983#endif /* KERNEL_PLL */ 984 freq_adj = drift_comp; 985 986 /* Bound absolute value of total adjustment to NTP_MAXFREQ. */ 987 if (offset_adj + freq_adj > NTP_MAXFREQ) 988 offset_adj = NTP_MAXFREQ - freq_adj; 989 else if (offset_adj + freq_adj < -NTP_MAXFREQ) 990 offset_adj = -NTP_MAXFREQ - freq_adj; 991 992 clock_offset -= offset_adj; 993 /* 994 * Windows port adj_systime() must be called each second, 995 * even if the argument is zero, to ease emulation of 996 * adjtime() using Windows' slew API which controls the rate 997 * but does not automatically stop slewing when an offset 998 * has decayed to zero. 999 */ 1000 DEBUG_INSIST(enable_panic_check == TRUE); 1001 enable_panic_check = FALSE; 1002 adj_systime(offset_adj + freq_adj); 1003 enable_panic_check = TRUE; 1004#endif /* LOCKCLOCK */ 1005} 1006 1007 1008/* 1009 * Clock state machine. Enter new state and set state variables. 1010 */ 1011static void 1012rstclock( 1013 int trans, /* new state */ 1014 double offset /* new offset */ 1015 ) 1016{ 1017 DPRINTF(2, ("rstclock: mu %lu state %d poll %d count %d\n", 1018 current_time - clock_epoch, trans, sys_poll, 1019 tc_counter)); 1020 if (trans != state && trans != EVNT_FSET) 1021 report_event(trans, NULL, NULL); 1022 state = trans; 1023 last_offset = clock_offset = offset; 1024 clock_epoch = current_time; 1025} 1026 1027 1028/* 1029 * calc_freq - calculate frequency directly 1030 * 1031 * This is very carefully done. When the offset is first computed at the 1032 * first update, a residual frequency component results. Subsequently, 1033 * updates are suppresed until the end of the measurement interval while 1034 * the offset is amortized. At the end of the interval the frequency is 1035 * calculated from the current offset, residual offset, length of the 1036 * interval and residual frequency component. At the same time the 1037 * frequenchy file is armed for update at the next hourly stats. 1038 */ 1039static double 1040direct_freq( 1041 double fp_offset 1042 ) 1043{ 1044 set_freq(fp_offset / (current_time - clock_epoch)); 1045 1046 return drift_comp; 1047} 1048 1049 1050/* 1051 * set_freq - set clock frequency correction 1052 * 1053 * Used to step the frequency correction at startup, possibly again once 1054 * the frequency is measured (that is, transitioning from EVNT_NSET to 1055 * EVNT_FSET), and finally to switch between daemon and kernel loop 1056 * discipline at runtime. 1057 * 1058 * When the kernel loop discipline is available but the daemon loop is 1059 * in use, the kernel frequency correction is disabled (set to 0) to 1060 * ensure drift_comp is applied by only one of the loops. 1061 */ 1062static void 1063set_freq( 1064 double freq /* frequency update */ 1065 ) 1066{ 1067 const char * loop_desc; 1068 int ntp_adj_ret; 1069 1070 (void)ntp_adj_ret; /* not always used below... */ 1071 drift_comp = freq; 1072 loop_desc = "ntpd"; 1073#ifdef KERNEL_PLL 1074 if (pll_control) { 1075 ZERO(ntv); 1076 ntv.modes = MOD_FREQUENCY; 1077 if (kern_enable) { 1078 loop_desc = "kernel"; 1079 ntv.freq = DTOFREQ(drift_comp); 1080 } 1081 if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) { 1082 ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 0, __LINE__ - 1); 1083 } 1084 } 1085#endif /* KERNEL_PLL */ 1086 mprintf_event(EVNT_FSET, NULL, "%s %.3f PPM", loop_desc, 1087 drift_comp * 1e6); 1088} 1089 1090 1091#ifdef KERNEL_PLL 1092static void 1093start_kern_loop(void) 1094{ 1095 static int atexit_done; 1096 int ntp_adj_ret; 1097 1098 pll_control = TRUE; 1099 ZERO(ntv); 1100 ntv.modes = MOD_BITS; 1101 ntv.status = STA_PLL; 1102 ntv.maxerror = MAXDISPERSE; 1103 ntv.esterror = MAXDISPERSE; 1104 ntv.constant = sys_poll; /* why is it that here constant is unconditionally set to sys_poll, whereas elsewhere is is modified depending on nanosecond vs. microsecond kernel? */ 1105#ifdef SIGSYS 1106 /* 1107 * Use sigsetjmp() to save state and then call ntp_adjtime(); if 1108 * it fails, then pll_trap() will set pll_control FALSE before 1109 * returning control using siglogjmp(). 1110 */ 1111 newsigsys.sa_handler = pll_trap; 1112 newsigsys.sa_flags = 0; 1113 if (sigaction(SIGSYS, &newsigsys, &sigsys)) { 1114 msyslog(LOG_ERR, "sigaction() trap SIGSYS: %m"); 1115 pll_control = FALSE; 1116 } else { 1117 if (sigsetjmp(env, 1) == 0) { 1118 if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) { 1119 ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 0, __LINE__ - 1); 1120 } 1121 } 1122 if (sigaction(SIGSYS, &sigsys, NULL)) { 1123 msyslog(LOG_ERR, 1124 "sigaction() restore SIGSYS: %m"); 1125 pll_control = FALSE; 1126 } 1127 } 1128#else /* SIGSYS */ 1129 if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) { 1130 ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 0, __LINE__ - 1); 1131 } 1132#endif /* SIGSYS */ 1133 1134 /* 1135 * Save the result status and light up an external clock 1136 * if available. 1137 */ 1138 pll_status = ntv.status; 1139 if (pll_control) { 1140 if (!atexit_done) { 1141 atexit_done = TRUE; 1142 atexit(&stop_kern_loop); 1143 } 1144#ifdef STA_NANO 1145 if (pll_status & STA_CLK) 1146 ext_enable = TRUE; 1147#endif /* STA_NANO */ 1148 report_event(EVNT_KERN, NULL, 1149 "kernel time sync enabled"); 1150 } 1151} 1152#endif /* KERNEL_PLL */ 1153 1154 1155#ifdef KERNEL_PLL 1156static void 1157stop_kern_loop(void) 1158{ 1159 if (pll_control && kern_enable) 1160 report_event(EVNT_KERN, NULL, 1161 "kernel time sync disabled"); 1162} 1163#endif /* KERNEL_PLL */ 1164 1165 1166/* 1167 * select_loop() - choose kernel or daemon loop discipline. 1168 */ 1169void 1170select_loop( 1171 int use_kern_loop 1172 ) 1173{ 1174 if (kern_enable == use_kern_loop) 1175 return; 1176#ifdef KERNEL_PLL 1177 if (pll_control && !use_kern_loop) 1178 stop_kern_loop(); 1179#endif 1180 kern_enable = use_kern_loop; 1181#ifdef KERNEL_PLL 1182 if (pll_control && use_kern_loop) 1183 start_kern_loop(); 1184#endif 1185 /* 1186 * If this loop selection change occurs after initial startup, 1187 * call set_freq() to switch the frequency compensation to or 1188 * from the kernel loop. 1189 */ 1190#ifdef KERNEL_PLL 1191 if (pll_control && loop_started) 1192 set_freq(drift_comp); 1193#endif 1194} 1195 1196 1197/* 1198 * huff-n'-puff filter 1199 */ 1200void 1201huffpuff(void) 1202{ 1203 int i; 1204 1205 if (sys_huffpuff == NULL) 1206 return; 1207 1208 sys_huffptr = (sys_huffptr + 1) % sys_hufflen; 1209 sys_huffpuff[sys_huffptr] = 1e9; 1210 sys_mindly = 1e9; 1211 for (i = 0; i < sys_hufflen; i++) { 1212 if (sys_huffpuff[i] < sys_mindly) 1213 sys_mindly = sys_huffpuff[i]; 1214 } 1215} 1216 1217 1218/* 1219 * loop_config - configure the loop filter 1220 * 1221 * LOCKCLOCK: The LOOP_DRIFTINIT and LOOP_DRIFTCOMP cases are no-ops. 1222 */ 1223void 1224loop_config( 1225 int item, 1226 double freq 1227 ) 1228{ 1229 int i; 1230 double ftemp; 1231 1232 DPRINTF(2, ("loop_config: item %d freq %f\n", item, freq)); 1233 switch (item) { 1234 1235 /* 1236 * We first assume the kernel supports the ntp_adjtime() 1237 * syscall. If that syscall works, initialize the kernel time 1238 * variables. Otherwise, continue leaving no harm behind. 1239 */ 1240 case LOOP_DRIFTINIT: 1241#ifndef LOCKCLOCK 1242#ifdef KERNEL_PLL 1243 if (mode_ntpdate) 1244 break; 1245 1246 start_kern_loop(); 1247#endif /* KERNEL_PLL */ 1248 1249 /* 1250 * Initialize frequency if given; otherwise, begin frequency 1251 * calibration phase. 1252 */ 1253 ftemp = init_drift_comp / 1e6; 1254 if (ftemp > NTP_MAXFREQ) 1255 ftemp = NTP_MAXFREQ; 1256 else if (ftemp < -NTP_MAXFREQ) 1257 ftemp = -NTP_MAXFREQ; 1258 set_freq(ftemp); 1259 if (freq_set) 1260 rstclock(EVNT_FSET, 0); 1261 else 1262 rstclock(EVNT_NSET, 0); 1263 loop_started = TRUE; 1264#endif /* LOCKCLOCK */ 1265 break; 1266 1267 case LOOP_KERN_CLEAR: 1268#if 0 /* XXX: needs more review, and how can we get here? */ 1269#ifndef LOCKCLOCK 1270# ifdef KERNEL_PLL 1271 if (pll_control && kern_enable) { 1272 memset((char *)&ntv, 0, sizeof(ntv)); 1273 ntv.modes = MOD_STATUS; 1274 ntv.status = STA_UNSYNC; 1275 ntp_adjtime(&ntv); 1276 sync_status("kernel time sync disabled", 1277 pll_status, 1278 ntv.status); 1279 } 1280# endif /* KERNEL_PLL */ 1281#endif /* LOCKCLOCK */ 1282#endif 1283 break; 1284 1285 /* 1286 * Tinker command variables for Ulrich Windl. Very dangerous. 1287 */ 1288 case LOOP_ALLAN: /* Allan intercept (log2) (allan) */ 1289 allan_xpt = (u_char)freq; 1290 break; 1291 1292 case LOOP_CODEC: /* audio codec frequency (codec) */ 1293 clock_codec = freq / 1e6; 1294 break; 1295 1296 case LOOP_PHI: /* dispersion threshold (dispersion) */ 1297 clock_phi = freq / 1e6; 1298 break; 1299 1300 case LOOP_FREQ: /* initial frequency (freq) */ 1301 init_drift_comp = freq; 1302 freq_set++; 1303 break; 1304 1305 case LOOP_HUFFPUFF: /* huff-n'-puff length (huffpuff) */ 1306 if (freq < HUFFPUFF) 1307 freq = HUFFPUFF; 1308 sys_hufflen = (int)(freq / HUFFPUFF); 1309 sys_huffpuff = emalloc(sizeof(sys_huffpuff[0]) * 1310 sys_hufflen); 1311 for (i = 0; i < sys_hufflen; i++) 1312 sys_huffpuff[i] = 1e9; 1313 sys_mindly = 1e9; 1314 break; 1315 1316 case LOOP_PANIC: /* panic threshold (panic) */ 1317 clock_panic = freq; 1318 break; 1319 1320 case LOOP_MAX: /* step threshold (step) */ 1321 clock_max_fwd = clock_max_back = freq; 1322 if (freq == 0 || freq > 0.5) 1323 select_loop(FALSE); 1324 break; 1325 1326 case LOOP_MAX_BACK: /* step threshold (step) */ 1327 clock_max_back = freq; 1328 /* 1329 * Leave using the kernel discipline code unless both 1330 * limits are massive. This assumes the reason to stop 1331 * using it is that it's pointless, not that it goes wrong. 1332 */ 1333 if ( (clock_max_back == 0 || clock_max_back > 0.5) 1334 || (clock_max_fwd == 0 || clock_max_fwd > 0.5)) 1335 select_loop(FALSE); 1336 break; 1337 1338 case LOOP_MAX_FWD: /* step threshold (step) */ 1339 clock_max_fwd = freq; 1340 if ( (clock_max_back == 0 || clock_max_back > 0.5) 1341 || (clock_max_fwd == 0 || clock_max_fwd > 0.5)) 1342 select_loop(FALSE); 1343 break; 1344 1345 case LOOP_MINSTEP: /* stepout threshold (stepout) */ 1346 if (freq < CLOCK_MINSTEP) 1347 clock_minstep = CLOCK_MINSTEP; 1348 else 1349 clock_minstep = freq; 1350 break; 1351 1352 case LOOP_TICK: /* tick increment (tick) */ 1353 set_sys_tick_precision(freq); 1354 break; 1355 1356 case LOOP_LEAP: /* not used, fall through */ 1357 default: 1358 msyslog(LOG_NOTICE, 1359 "loop_config: unsupported option %d", item); 1360 } 1361} 1362 1363 1364#if defined(KERNEL_PLL) && defined(SIGSYS) 1365/* 1366 * _trap - trap processor for undefined syscalls 1367 * 1368 * This nugget is called by the kernel when the SYS_ntp_adjtime() 1369 * syscall bombs because the silly thing has not been implemented in 1370 * the kernel. In this case the phase-lock loop is emulated by 1371 * the stock adjtime() syscall and a lot of indelicate abuse. 1372 */ 1373static RETSIGTYPE 1374pll_trap( 1375 int arg 1376 ) 1377{ 1378 pll_control = FALSE; 1379 siglongjmp(env, 1); 1380} 1381#endif /* KERNEL_PLL && SIGSYS */ 1382