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List:       aic7xxx
Subject:    Question on MMAPIO ...
From:       Patrick Mau <patrick () oscar ! prima ! de>
Date:       1998-08-31 3:10:57
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Dear Adaptec Users,

I have a question regarding memory-mapped I/O with linux.
I'm using a pretty old AHA3940 PCI Dual Channel PCI controller and
ever since MMAPIO is defined in this driver I have to undefine it.

I'm sure this is a hardware/timing problem so my problem might
be a bit offtopic for driver development. With MMAPIO defined the
kernel locks hard when syncing buffers to disk. These hard locks do
_always_ happen, regardless of heavy or light bus traffic.

If MMAPIO is not defined the driver works without any problems. I've
double-checked termination and cables, switched cards to differnt PCI
slots and so on. I just want to know if other people expirienced
similar problems.

It would be nice if someone could explain the difference between
memory-mapped and traditional I/O. I don't understand why the driver
works with this small change.

BTW, I did not overclock my system. All hardware is used within
specification.

any comment is greatly appreciated,

Patrick


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