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RE: more issues with root fs.

To: linux-mips@fnet.fr
Subject: RE: more issues with root fs.
From: Harald Koerfgen <Harald.Koerfgen@home.ivm.de>
Date: Mon, 25 Jan 1999 23:17:24 +0100 (MET)
In-reply-to: <Pine.LNX.3.96.990124204614.19805B-100000@apt4g.a3nyc.com>
Organization: none
Reply-to: "Harald Koerfgen" <Harald.Koerfgen@home.ivm.de>
Sender: harry@franz.no.dom
Hi,

On 25-Jan-99 Thomas Riemer wrote:
> 1. I'm getting errors that my Makefiles have modifications in the
> future.
> 2. I'm getting errors that make is detecting a clock skew.
> 3. I do not have CONFIG_RTC set in the kernel.
> 4. /sbin/clock doesn't exist.
> 
> Somehow I think all of these are related to some basic problem with
> time in the kernel?  Does this stuff work on someone elses machine?

Yes, it does on mine :-). Well, not really, the patch isn't ready for
rollout yet.

The cause is that the DECstation timer tick is running at 128 Hz and all
the userland binaries think that the kernel is running at 100 Hz, which is
the standard for Linux except for Alpha machines. BTW, DECstation-Linux
2.1.121 was running at 64 HZ.

So we have two possibilities here:

One is to recompile all userland binaries with HZ=128, thus not beeing able
to use, for example, the Cobaltmicro rpms. Not very good.

The second one is to pretend to userland, the kernel is running at 100 Hz.
The kernel itself is prepared for HZ != 100, otherwise it would not be
working on Alphas. The culprit are functions where the jiffies or
derivatives of that are exported to userland. I am working on this.

Fellow DECstation hackers, please do *not* use CONFIG_RTC. The RTC is the
only possible source for periodic interrupts on the DECstations and the
RTC driver likes to play around with that causing bad things to happen. We
have to disable some features in drivers/char/rtc.c before it's safe to
use it.

---
Regards,
Harald

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