linux-mips-fnet
[Top] [All Lists]

Re: DECstation rtc driver

To: Harald Koerfgen <Harald.Koerfgen@home.ivm.de>
Subject: Re: DECstation rtc driver
From: Ralf Baechle <ralf@uni-koblenz.de>
Date: Tue, 28 Mar 2000 19:10:00 +0200
Cc: linux-mips@fnet.fr
In-reply-to: <XFMail.000328172240.Harald.Koerfgen@home.ivm.de>
References: <20000327223734.A3523@uni-koblenz.de> <XFMail.000328172240.Harald.Koerfgen@home.ivm.de>
On Tue, Mar 28, 2000 at 05:22:40PM +0200, Harald Koerfgen 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?
> 
> Sad, but true. The DECstation engineers, in their infinite wisdom, decided to
> use the RTC chip as a TOY (Time Of Year clock) and as such the BootPROM allows
> only the years 70..72 as valid values (70 for even years, 71 for odd years, 
> and
> 72 for leap years).
> 
> Otherwise you'll get a self test failure and the date will be reset, as Maciej
> already pointed out. And yes, this code has to be modified every two years :(.

Sounds really bad - but regular kernel patching isn't an option either.
You could use some sliding window solution in combination with a time stored
on disk.

  Ralf

<Prev in Thread] Current Thread [Next in Thread>