From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt To: Gabriel Paubert , Subject: Re: rtc again... Date: Thu, 10 Aug 2000 00:48:02 +0200 Message-Id: <20000809224802.27760@192.168.1.10> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: >I strongly suspect that we might want a single rtc access function in >ppc_md and add a first parameter telling what we want it to do, the second >being a pointer to a tv_sec, and perhaps more parameters. > >[.../...] > >This last function could also be performed by returning the timebase in >the READ_TIME function as an extra parameter. The best solution is the one >which gives the minimal permanent kernel size, __init code size is >irrelevant. Ok. >What use does it have if no daemon will change the timezone anyway ? Well, when travelling with a PowerBook, you tend to regulary change the timezone, and you like the kernel to remember what it was ;) Paul added the write back of the sys_tz, so I beleive he has some userland tool to set it too, Paul ? With this current code, any write to our pmac-specific /dev/rtc will cause ppc_md.set_rtc_time to update both the RTC and the xpram sys_tz. So either we make a userland tool for that, or eventually add such a feature to pmud along with other PowerBook-specific tasks, accessing / dev/nvram directly, or we find a way to make sure updates to sys_tz are written back to nvram. I was not specifically thinking about results of a DST change. We could eventually add this code along with other nvram write code (for flash based nvram) in the restart/shutdown routines if we don't want to do it from every ppc_md.set >How does MacOS handle DST changes (on the fly or only at reboot) ? On the fly. >You never (well hardldy ever) pass localtime to userland in Unix and >that's a big big big plus, each process/user can set TZ as it wishes. IOW >the value of sys_tz is at best a system wide default but is not imposed to >anybody. Here at the telescope on all Linux machines, /etc/localtime is >set as UTC, but then I set TZ=Europe/Madrid in my .profile to avoid too >much confusion with my PC which has localtime set to Europe/Madrid. And >right now I am running a shell with TZ set to Pacific/Tahiti to believe >that I'm on holiday ;-) Ok, I understand that. That's indeed a nice feature. Changing the "global" timezone is specifically useful for portables. You can consider it as the machine's physical location instead of a kind of "global" timezone. >Done and booted (although I will probably orphan the changeset). Heh ;) Ben. ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/