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Date:      Thu, 16 Apr 1998 00:17:30 -0600 (MDT)
From:      "Justin T. Gibbs" <gibbs@narnia.plutotech.com>
To:        Tom <tom@uniserve.com>
Cc:        current@FreeBSD.ORG
Subject:   Re: Help - please... Adaptec 1542 and Exabyte tape problem...
Message-ID:  <199804160617.AAA28394@narnia.plutotech.com>
In-Reply-To: <Pine.BSF.3.96.980415225257.15072A-100000@shell.uniserve.com>

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In article <Pine.BSF.3.96.980415225257.15072A-100000@shell.uniserve.com> you wrote:
> 
> On Thu, 16 Apr 1998, Kerry Morse wrote:
> 
>> Apr 16 13:35:05 proxy /kernel: aha0: DMA beyond end Of ISA: 0x357cd10
> 
>   Bounce buffers are required to DMA above the 16MB for ISA devices.
> However, bounce buffers do not work for the aha driver (it is unclear
> whether the driver or the bounce buffers are broken).

It's not the driver, and it's not the bounce buffers.  It's the fact
that several portions of the SCSI layer allocate objects that are
the targets of DMA on the kernel stack and that a clude in scsi_scsi_cmd()
to detect this and properly bounce the data does not work.

>   This is any old problem.  See the archives.  It seems that any developer 
> who has more than 16MB of RAM has also decided to upgrade to non-ISA
> controllers.

Bah.  I implemented the Bus DMA version of bounce buffers just so ISA
AdvanSys and Adaptec cards could be properly supported.  The 1542 driver
simply hasn't been completed yet for CAM.

> Tom

--
Justin

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