Comment # 81 on bug 925873 from Dr. Werner Fink

(In reply to Stanislav Brabec from comment #72)

> Werner: It needs some way of global configuration:
> 
> - --hctosys on resume is a work around. Good systems should always update 
> system time.

Normally the kernel does this at boot ... therefore in mkinitrd/dracut the
kernels system clock has to warped if local time is or has to be used for the
hardware clock *before* file system checks and mounting them.

> 
> - --systohc on suspend/shutdown makes sense for systems with bad hwclock. But 
> adjtime must be disabled then.

ACK

> - --systohc on suspend/shutdown also makes sense on systems with NTP. But 
> regular --systohc (e. g. once or twice daily) just after NTP update makes 
> even more sense.

Here the matrix has to expanded, that is if ntp service is running then the
kernel may stay in elven minutes mode (bit 64 in the status line return by
adjtimex is *not* set -> STA_UNSYNC[1]) there is no need to perfom system clock
to hw clock.

> - regular --hctosys and regular --adjust makes sense for systems with bad 
> system clock. But systohc on suspend/shutdown must be disabled then.
> 
> I guess we should create global sysconfig for them. This quirk can be easily 
> transformed to systemd quirk, so the result will not be dependent on pm-utils.

ACK


[1]
/usr/include/bits/timex.h

/* Status codes (timex.status) */
#define STA_PLL         0x0001  /* enable PLL updates (rw) */
#define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
#define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
#define STA_FLL         0x0008  /* select frequency-lock mode (rw) */

#define STA_INS         0x0010  /* insert leap (rw) */
#define STA_DEL         0x0020  /* delete leap (rw) */
#define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
#define STA_FREQHOLD    0x0080  /* hold frequency (rw) */

#define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
#define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
#define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
#define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */

#define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */
#define STA_NANO        0x2000  /* resolution (0 = us, 1 = ns) (ro) */
#define STA_MODE        0x4000  /* mode (0 = PLL, 1 = FLL) (ro) */
#define STA_CLK         0x8000  /* clock source (0 = A, 1 = B) (ro) */