Re: Kernel reboot on loading (port 0xEF)

From: Richard B. Johnson (root@chaos.analogic.com)
Date: Tue Jul 25 2000 - 07:07:39 EST


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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