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smart
Guru
Joined: 19 Nov 2002
Posts: 455
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 Posted: Wed May 26, 2004 11:46 am Post subject: Blade 100 & DMA on IDE |
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Hi there...
last state i was updated with is that using DMA for the IDE chipset on Blade 100 should be avoided due to incompatibilities possibly resulting in filesystem corruption... which i was able to verify from the backside of the coin.
Now in the sample config given on http://dev.gentoo.org/~ciaranm/configs/kernel/2.6.x/kernel-2.6.4-blade100.config.gz
that DMA is activated. Have i missed that the kernel been modified to support it since ? |
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moocha
Watchman
Joined: 21 Oct 2003
Posts: 5722
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| Posted: Wed May 26, 2004 12:29 pm Post subject: |
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Now, I don't have any experience with the SPARC architecture, but I may be able to help nevertheless.
From what I gather the Blade 100 uses the ALi 15x3 (actually M5229) ATA controller.
I used to have an x86 PC using the ALi Alladin V chipset that used the same controller. The controller revisions 0x20 and older indeed are said to contain some bugs - but it worked for years for me in UltraDMA Mode 2 (ATA33) without a hitch. Then the bug surfaced and ALi released the M1543C chipset (I presume C stands for Corrected *snicker*) and dropped any and all references to the original chipset from their site, pretending it never existed (they also refused to provide support, grr). Both ALi's Windows drivers and the Linux kernel driver dropped me into PIO mode (evil, CPU usage 100%). Hacking drivers/ide/pci/alim15x3.c to forcibly report UDMA capability allowed me to use UDMA just fine.
Lately it seems to have been confirmed that at least Multiword DMA mode 2 works fine - which is what I'm willing to bet the kernel's libata falls back to. Run (or whatever your device node may be) - that asterisk is probably next to mdma, not udma.
Run and look for the M5229 controller revision in the output. From what I gathered from the driver source, revisions earlier than 0x20 can't do any DMA, 0x20 is supposed to be buggy and to be able to correctly do only MDMA mode 2 (but again, for me it worked in UDMA mode 2 for years without a single problem), 0xC0 is supposed to do UDMA mode 0 (it probably can do up to 2 at least, since it's newer than 0x20, but I don't know), and only revision 0xC4 and later know UDMA mode 5 (ATA100).
If you're interested, I can provide a patch to alim15x3.c that will let you use UDMA - but I'm not going to guarantee that your drive won't blow up and/or your cat won't get run over by a truck because of it 
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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."
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smart
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Joined: 19 Nov 2002
Posts: 455
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| Posted: Tue Jun 01, 2004 7:11 pm Post subject: |
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Hi again,
thanks for the info. This is what i get from lspci...
0000:00:0d.0 IDE interface: ALi Corporation M5229 IDE (rev c3) (prog-if ff)
Flags: bus master, medium devsel, latency 64, IRQ 006eaf80
I/O ports at 0000000002000a00
I/O ports at 0000000002000a18 [size=4]
I/O ports at 0000000002000a10 [size=8]
I/O ports at 0000000002000a08 [size=4]
I/O ports at 0000000002000a20 [size=16]
Capabilities: [60] Power Management version 2
So my assumption using yourinfo would be that it *should* do DMA without problems ? |
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moocha
Watchman
Joined: 21 Oct 2003
Posts: 5722
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| Posted: Tue Jun 01, 2004 7:56 pm Post subject: |
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Yes. Revision 0xc3 (you have that) should do at least UDMA mode 2 without any trouble. However the kernel driver won't allow you to do that unless you modify it and tell it to not be so trusting of ALi's press releases.
_________________
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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smart
Guru
Joined: 19 Nov 2002
Posts: 455
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| Posted: Tue Jun 22, 2004 3:53 pm Post subject: |
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| Meanwhile, though i have not enabled DMA, disk access is fuckered up again. It seems to me something is seriously wrong, either with my machine, that disc or the drivers. |
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