From owner-freebsd-current  Fri Jan 28  9: 9:16 2000
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Date: Fri, 28 Jan 2000 17:08:40 +0100
From: "D. Rock" <rock@dead-end.net>
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To: current@freebsd.org
Subject: ata: panic with new sysctl variable
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Hi,

just noticed the new sysctl variable for ata. I just wanted to
use the new way for disabling DMA on my disk (has some strange
problems, even under windows).

Previously I just commented out the ata_dmainit() lines in
ata_disk.c, now I wanted to set it with sysctl:

sysctl -w hw.atamodes="pio,dma,dma,dma"

but this paniced my machine.

I later discovered that there is no sanity check during setting
the new modes: The machine in question didn't have a secondary
IDE controller, but the variables were set without a range check.

My solution was simple. Just use
sysctl -w hw.atamodes="pio,dma"

but I think, the ata driver should range check the settings.

Daniel


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