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Date:      Thu, 20 Apr 2000 12:05:21 -0700
From:      Kent Stewart <kstewart@3-cities.com>
To:        Arcady Genkin <a.genkin@utoronto.ca>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Selectively enable/disable DMA for an ata driver
Message-ID:  <38FF54F1.F6CC270C@3-cities.com>
References:  <87og74d9j6.fsf@tea.thpoon.com>

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Do a "man ata" and in the middle is a section on the sysctl options
that you can use to set ad0 to PCI. You now have a /etc/sysctl.conf
for saving options such as this one.

Kent

Arcady Genkin wrote:
> 
> I have two HD: one supports DMA, the other doesn't. When I was running
> 3.4, I used to selectively turn on such features for each drive with
> flags. Now it seems like there is only "options ATA_ENABLE_ATAPI_IDE",
> which is global.
> 
> How would I work around that?
> 
> ,----[ Currently I have ]
> | device          ata0    at isa? port IO_WD1 irq 14
> | device          ata1    at isa? port IO_WD2 irq 15
> | device          ata
> | device          atadisk
> | options         ATA_STATIC_ID           #Static device numbering
> | options         ATA_ENABLE_ATAPI_DMA
> `----
> ,----[ I used to have ]
> | controller      wdc0    at isa? port "IO_WD1" bio irq 14 flags 0x90ff90ff
> | disk            wd0     at wdc0 drive 0
> | controller      wdc1    at isa? port "IO_WD2" bio irq 15 flags 0xb0ffb0ff
> | disk            wd2     at wdc1 drive 0
> `----
> 
> It seems like both drives are initialized in DMA mode:
> ,----[ dmesg ]
> | ad0: 2014MB <WDC AC22100H> [4092/16/63] at ata0-master using WDMA2
> | ad2: 18366MB <QUANTUM BIGFOOT TS19.2A> [37317/16/63] at ata1-master using WDMA2
> `----
> 
> I know for sure that ad0 does not support DMA, and has a habbit of
> slowing down considerably if used with DMA (I remember from the time
> when I experimented with different flags for the `wdc' driver).
> 
> Thanks for any insight!
> --
> Arcady Genkin                                 http://www.thpoon.com
> Nostalgia isn't what it used to be.
> 
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-- 
Kent Stewart
Richland, WA

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