On Nov 22, 2011 5:58 PM, "Kay Sievers" <<a href="mailto:kay.sievers@vrfy.org">kay.sievers@vrfy.org</a>> wrote: > > On Tue, Nov 22, 2011 at 23:42, Martin Langhoff > <<a href="mailto:martin.langhoff@gmail.com">martin.langhoff@gmail.com</a>> wrote: > > On Tue, Nov 22, 2011 at 3:21 PM, Kay Sievers <<a href="mailto:kay.sievers@vrfy.org">kay.sievers@vrfy.org</a>> wrote: > >> Yeah, that's intentional. Udev on other platforms can't know which rtc > >> should be the preferred one. > > > > Well, now you can: if it says hctosys == 1, it means that the kernel > > config told it to pick that one, and that it's sync'd the system time > > to it. > > You have rtc1 set in the kernel config for your box? Correct. And rtc0 is only good for rtcwake -- won't hold "real" clock time, because it isn't battery-backed. "My box" is the XO-1.75 platform, of which we expect a few million will be produced starting soon. Future kernels may bring them up in different order, but that's a different pile of pain. > >> This link is mainly for backwards compat, because in earlier days it > >> was a real kernel device. > > > > Well, the symlink has a very practical use! If you have several RTCs, > > you can use udev to symlink rtc to it, and it gets htclock to DTRT. > > > > On our XO-1.75, the "real" rtc is rtc1. > > > > Next, we got to get src/utils.c to prefer "rtc" if it finds it ;-) > > I guess udev should claim /dev/rtc for the rtc device that has hctosys == 1 set? Yep. It's a trivial udev rule, perhaps belongs to Fedora's initscripts? cheers, m { Martin Langhoff - one laptop per child }