| Util-linux has always had the clock program (by Charles Hedrick, |
| Rob Hooft, Harald Koenig, Alan Modra). |
| |
| Slackware still uses the clock.c and clock.8 from util-linux-2.6 |
| (and calls the resulting source fragment clock-1.6.tar.gz). |
| |
| Bryan Henderson rewrote it, calling the result hwclock, |
| and util-linux-2.6 has both clock.c and hwclock.c, |
| util-linux-2.7 and later only have hwclock.c. |
| |
| Unfortunately, hwclock.c was broken in various ways, especially |
| on non-intel hardware, and distributions started shipping private |
| versions (usually derived from the old clock). |
| |
| For util-linux-2.9k Andries Brouwer took all clock versions around, |
| and merged them. The resulting hwclock program works on all architectures. |
| There are some kernel bugs in the handling of /dev/rtc on some i386 hardware, |
| so under certain circumstances where hwclock fails one has to give it the |
| --directisa flag to let hwclock do the clock access itself (which works) |
| rather than leave it to the kernel. [The precise cause is still being |
| investigated.] |
| This is the code presently found in the clock subdirectory. |
| |
| Bryan Henderson took this code again and merged it with his original |
| hwclock source. That is the code found in the util-linux-2.9q clock |
| directory. Unfortunately, this new version didnt work on Sparcs |
| and in util-linux-2.9r this code was moved to the clockB subdirectory. |
| |
| |
| Executive summary: |
| clock/hwclock is claimed to be good (but may need the --directisa flag). |
| |
| |
| Comments, bug reports etc are welcome. |
| Note that the source contains a rather detailed description of the clock |
| hardware involved. Additions and corrections are welcome. |
| |
| Andries |
| aeb@cwi.nl |
