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Re: more issues with root fs.

To: linux-mips@fnet.fr
Subject: Re: more issues with root fs.
From: "Paul M. Antoine" <paul@milleng.com.au>
Date: Wed, 27 Jan 1999 08:00:46 +1100
Organization: Millennium Engineering Pty Ltd
References: <XFMail.990125231724.Harald.Koerfgen@home.ivm.de>
Harald Koerfgen wrote:

> 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.

If you look at the Mach sources you'll see reference to their clock
routines
making use of a regular hardware timer interrupt, at least on the
Maxine...
which interrupts more often than the RTC can at a fixed rate and is used
to
create a 100hz timer. I'll have to dig through some source again to find
those
references and to see if all models of DECstation have something
similar, but
this could be a solution.

Regards,
Paul
______________________________________________________________________________
Paul M. Antoine                                 Millennium Engineering
Pty Ltd
email: paul@milleng.com.au                              Phone: +61 2
9560 7331
large files: pantoine@nsw.bigpond.net.au                Fax:   +61 2
9560 8708

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