From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <eaab38172bc39a6c03a6f2b05f20788e@quanstro.net>
To: 9fans@9fans.net
From: erik quanstrom <quanstro@quanstro.net>
Date: Tue,  5 Aug 2008 15:01:30 -0400
In-Reply-To: <13426df10808051126t3f517cdcj2d13be003d6ba877@mail.gmail.com>
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Subject: Re: [9fans] Bizarre freeze
Topicbox-Message-UUID: fb2a8726-ead3-11e9-9d60-3106f5b1d025

>> I wonder why there is a command to turn on DMA on disks.  Could
>> it be that some disks don't work with DMA on?
>
> sure. it's PC hardware, so it's crap :-)
> ron

the ata spec does not require dma for pata devices.
sata, first specified in ata 7, requires udma mode 5,
though sata:pata bridges routinely do not.

it's impossible to know without a bit more information,
but the dma command may be a red herring.

>  sdC0 is a cdrom. I can turn dma on for my sata disks (sdE0/sdF0) no problem.

can you access the cdrom at all?  i'm wondering if
you're accessing a ahci-capable chipset in ahci *and*
ata modes at the same time.

- erik