Hi Dick.
Reading from port 0xEE yields 0xff and nothing seems to happen, but actually
it is an alternative method to propagate the A20 signal.
But if you read from port 0xEF (in the bios debugger) the Elan SC400
reboots.
That is why I'm wondering if the kernel reads that port somewhere, maybe as
a part of checking what ports are available ?
Agust Karlsson
Pallas Informatik
Alleroed Stationsvej 2D
DK-3450 Alleroed Denmark
Tel: +45 4810 2410
Fax: +45 4810 2401
> -----Original Message-----
> From: Richard B. Johnson [SMTP:root@chaos.analogic.com]
> Sent: 25. juli 2000 14:08
> To: Agust Karlsson
> Cc: 'linux-kernel@vger.rutgers.edu'
> Subject: Re: Kernel reboot on loading (port 0xEF)
>
> On Tue, 25 Jul 2000, Agust Karlsson wrote:
>
> > Hi once again.
> >
> > Now I think I have found the reason that the kernel reboots itself on
> > loading.
> > It turnes out that the AMD Elan SC400 microcontroller has an alternative
> CPU
> > reset by
> > reading (yes reading) port 0xEF.
> > Does anyone know if linux reads this port and if so where should I look
> for
> > it.
>
> I don't think this is correct. I can DOS-boot the Elan SC400 development
> board and, using DEBUG, inp from port 0xEF with no effect. Further, the
> value read is 0xFF, so it's likely it's not even decoded.
>
> You might have something plugged into an ISA slot that's screwing up
> the timing so badly that I/O at many aliases will reboot. Linux
> uses port 0x80 for "slow down I/O". Other ports are specific for the
> various devices.
>
>
> Cheers,
> Dick Johnson
>
> Penguin : Linux version 2.2.15 on an i686 machine (797.90 BogoMips).
>
> "Memory is like gasoline. You use it up when you are running. Of
> course you get it all back when you reboot..."; Actual explanation
> obtained from the Micro$oft help desk.
>
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