Subject: Re: DMA beyond end of ISA with other scsi cards?
To: Scott Reynolds <scottr@Plexus.COM>
From: Justin T. Gibbs <firstname.lastname@example.org>
Date: 11/13/1996 14:51:05
>On Tue, 12 Nov 1996, Justin T. Gibbs wrote:
>> Well considering Leonard's sources, I doubt that he is wrong. Here is
>> what the Linux Buslogic driver has to say about this:
>> BusLogic BT-445S Host Adapters prior to board revision E have a
>> hardware bug whereby when the BIOS is enabled, transfers to/from the
>> same address range the BIOS occupies modulo 16MB are handled
>> incorrectly. Only properly functioning BT-445S boards have firmware
>> version 3.37, so we require that ISA Bounce Buffers be used for the
>> buggy BT-445S models if there is more than 16MB memory.
>My board has firmware version 3.37; does the comment above mean that this
>is why I'm not having any problems? It isn't clear to me exactly what the
>above means, at any rate. :-)
It means that any time you transfer to memory in the range of
(X * 16MB) + BIOS offset to (X * 16MB) + BIOS offset + BIOS size, you lose.
It appears that 3.37 is okay.
Justin T. Gibbs
FreeBSD: Turning PCs into workstations