Re: L68K: Re: Afterburner and Linux

From: Doug Little <doug_at_innerworkings.co.uk>
Date: Mon, 8 Jun 1998 10:45:40 +0100

>Yes, I agree. I chatted with Uwe Seimet and he mean something like that
>(I don't know exactly). This is also the problem why logging SCSI-drives
>at bootup only works with data cache off.


It seems that whatever HDDriver is doing during SCSI logging, the problem
is simply due to the CPU cacheing stale data.

That means it's either hardware registers being cached - which should not
be possible so long as they lie in the usual address space for hardware
(the top 1mb or so of the address space), or HDDriver is using DMA to get
information from the SCSI device, and the DMA operation is taking place
in some area of cacheable ST-ram. I think the latter is likely. In which
case,
HDDriver should deal with it by making sure the caches are off during the
logging process.

Doug.
Received on ma. juni 08 1998 - 18:34:00 CEST