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Re: DECstation rtc driver

To: Ralf Baechle <ralf@uni-koblenz.de>
Subject: Re: DECstation rtc driver
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Tue, 28 Mar 2000 11:04:12 +0200 (MET DST)
Cc: Harald Koerfgen <Harald.Koerfgen@home.ivm.de>, linux-mips@fnet.fr
In-reply-to: <20000327223734.A3523@uni-koblenz.de>
Organization: Technical University of Gdansk
On Mon, 27 Mar 2000, Ralf Baechle wrote:

> around line 676.  This means that only two the years 1998 to 2000 will be
> recognized for the `Digital DECstation Epoch'.  Looks broken to me.  I
> tried to fix it but don't know the secrets of DECstation RTC timekeeping so
> could a DECstation guru look at it?

 DECstations can only handle 1972 and 1973 years in the RTC clock.  If any
other year is written into the chip, the firmware will reset the clock
back to Jan 1st, 1972 ASAP.  Yes, its weird -- I have no idea why it was
implemented this way.

 I'm thinking of a workaround using one of the general-purpose RTC RAM
locations.  The firmware uses most of the RAM but two bytes seem to be
unused; at least I was unable to convince the firmware to modify them
spontaneously (I don't mean the deposit command, of course).  I'm not sure
whether they are used or not by Ultrix and OSF/1, though.  It could be a
problem for dual boot setups.

 For now, the code must remain as is, I suppose.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +

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