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Chriske
Tux's lil' helper
Joined: 09 Apr 2004
Posts: 86
Location: Belgium (Antwerp)
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 Posted: Sun Dec 04, 2005 10:20 pm Post subject: ALi M5229 rev c7 |
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I have a motherboard with an ALi M5229 (rev c7) IDE interface and, of course, want to have DMA enabled After searching the forums and googling around a bit, i found that the ALI15X3-driver is supposed to support this chipset (at least some of the revisions of it). So i tried it, compiled it into the kernel and booted. The result was a kernel panic (could not mount root on block yadayada).
After this i tried turning the ALI M15x3 WDC support, knowing it was dangerous, but it was an empty HD anyway, so it didn't really matter. Still got the same kernel panic.
Then i tried it with the Generic PCI IDE Chipset Support, and the kernel booted. But i could not turn on DMA of course.
After playing around a bit i tried theALI15X3 chipset support agein, but turned off "Use PCI DMA by default when available". To my surprise, the kernel booted. And, even more surprising, i can turn on DMA on my HD.
So now i just put this in /etc/conf.d/local.start: | Code: | | /sbin/hdparm -q -d1 /dev/hda |
and now i only have a little slowdown during started (e.g. fsck).
Although this workaround works, the problem is pretty strange to me. Why can't DMA be turned on automatically during boot, but it can afterwards. Anyone have an idea?
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moocha
Watchman
Joined: 21 Oct 2003
Posts: 5722
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| Posted: Sat Dec 10, 2005 2:56 pm Post subject: |
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(Semi-educated guess, been forced to hack around the ALi controller driver a lot to get UDMA a few years back): The code that determines whether to actually turn on DMA by itself during boot thinks it's not safe and prefers to err on the safe side.
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"Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety."
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Chriske
Tux's lil' helper
Joined: 09 Apr 2004
Posts: 86
Location: Belgium (Antwerp)
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| Posted: Sun Dec 11, 2005 12:00 pm Post subject: |
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So what do you sugest?
I 've heard about wrong version checks, which could be overriden by changing the "can_ultra()" function in the ALi-driver. But this didn't really help.
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moocha
Watchman
Joined: 21 Oct 2003
Posts: 5722
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| Posted: Sun Dec 11, 2005 5:46 pm Post subject: |
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Well, you can either patch the driver, or (safest) just ignore the issue and do what you're doing currently, i.e. forcing DMA on manually in the init scripts.
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Military Commissions Act of 2006: http://tinyurl.com/jrcto
"Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety."
-- attributed to Benjamin Franklin |
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