*BSD News Article 78380


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From: tedm@agora.rdrop.com
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: BOUNCE BUFFERS AND BUSLOGIC ISA CONTROLLER
Date: 16 Sep 1996 08:15:17 GMT
Organization: Symantec Corporation
Lines: 13
Message-ID: <51j2al$qub@symiserver2.symantec.com>
References: <323735BE.41C67EA6@mindspring.com> <51enth$t3q@symiserver2.symantec.com> <51hsmr$170@main.gbdata.com>
Reply-To: tedm@agora.rdrop.com
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In <51hsmr$170@main.gbdata.com>, gclarkii@main.gbdata.com (Gary Clark II) writes:
>Panics on a 486 with 32MB and a 545 SCSI card.
>
>The fix for DMA > 16MB is to add 'option BOUNCE_BUFFERS' to the kernel
>config file, recompile, reinstall and reboot.  By nature DMA > 16MB
>on the ISA buss is broken.

The problem with this is that the device driver must understand this for it to
work, or so I believe after looking at the driver code.  While I think most or all
of the SCSI drivers do understand it, there are a number of network adapter
card drivers that use DMA and thus have the same problem.  You cannot blindly
assume that compiling with bounce buffers defined is going to fix the problem,
you still need to check the driver source.