110 lines
4.0 KiB
HTML
110 lines
4.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>The Linux Ultra-DMA Mini-Howto: Problems</TITLE>
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<LINK HREF="Ultra-DMA-10.html" REL=next>
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<LINK HREF="Ultra-DMA-8.html" REL=previous>
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<LINK HREF="Ultra-DMA.html#toc9" REL=contents>
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</HEAD>
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<BODY>
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<A HREF="Ultra-DMA-10.html">Next</A>
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<A HREF="Ultra-DMA-8.html">Previous</A>
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<A HREF="Ultra-DMA.html#toc9">Contents</A>
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<HR>
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<H2><A NAME="s9">9. Problems</A></H2>
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<H2><A NAME="blacklist"></A> <A NAME="ss9.1">9.1 The UDMA Blacklist</A>
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</H2>
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<P>
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<P>The following drives are ``blacklisted''. You should <B>not</B> use UDMA with
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these drives as it may cause corruption of data. To avoid this, the driver
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should automatically disable DMA for these drives.
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<P>
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<UL>
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<LI>Western Digital WDC AC11000H, AC22100H, AC32500H, AC33100H, AC31600H - all versions</LI>
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<LI>Western Digital WDC AC32100H revision 24.09P07</LI>
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<LI>Western Digital WDC AC23200L revision 21.10N21</LI>
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</UL>
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<P>
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<H2><A NAME="ss9.2">9.2 Are you overclocking?</A>
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</H2>
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<P>
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<P>If you are, beware! Here is a quote from the old udma-generic documentation:
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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DON'T OVERCLOCK the PCI bus. 37.5MHz is the maximum supported speed for
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the PCI bus. Some (supposedly compatible) UDMA drives will not even take
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37.5MHz, but should be OK at 33.3MHz.
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In any case, NEVER, NEVER set the PCI bus to 41.5MHz.
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The RECOMMENDED safe setting is 33MHz.
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>
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<H2><A NAME="ss9.3">9.3 Is your BIOS current?</A>
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</H2>
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<P>
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<P>Here is another clip from the udma-generic docs:
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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The real work involved in setting up the chips for DMA transfers is done
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mostly by the BIOS of each motherboard. Now of course one hopes that the
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BIOS has been correctly programmed...
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For example, the ASUS SP-97V motherboard with its original BIOS (Rev. 1.03)
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would malfunction with the modified Linux driver in both DMA mode 2 and UDMA
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modes; it would work well using PIO mode 4, or under Windows 95 in all
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modes. I downloaded the latest BIOS image (Rev. 1.06) from the ASUS Web site
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and flashed the BIOS EPROM with the latest BIOS revision. It has been
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working perfectly ever since (at 66 MHz bus speeds).
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What this tells us is that the BIOS sets up the DMA controller with specific
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timing parameters (active pulse and recovery clock cycles). My initial BIOS
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revision probably had bad timings. Since the Windows 95 driver sets up those
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timings by itself (i.e. it does not depend on the BIOS to setup the hard
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disk controller timing parameters), I initially had problems only with the
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Linux driver, while Windows 95 worked well.
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So, let me state this again: this Linux (U)DMA driver depends on the BIOS for
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correct (U)DMA controller setup. If you have problems, first check that you
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have the latest BIOS revision for your specific motherboard.
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...
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New BIOS revisions can be downloaded from your motherboard manufacturer's
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Web site. Flashing a new BIOS image is a simple operation but one must
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strictly follow the steps explained on the motherboard manual.
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Late Award BIOS revisions seem stable with respect to UDMA. Anything with a
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date of 1998 should be fine.
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>
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<H2><A NAME="help"></A> <A NAME="ss9.4">9.4 If you still can't get it to work!</A>
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</H2>
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<P>
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<P>If nothing in this document proved helpful, or at least not helpful enough
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to get your machine working, your best bet is to write up a message that
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fully describes your difficulty, what type of UDMA interface you have,
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whether it is onboard or on a card, if your drive is actually UDMA or plain
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EIDE, exactly what configuration of drives you have, what version (distribution
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& kernel versions if possible) of Linux you are using, and anything
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else that sounds useful, and post it to the newsgroup
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<A HREF="news:comp.os.linux.hardware">comp.os.linux.hardware</A>.
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You will probably get some helpful suggestions soon.
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<P>
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<HR>
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<A HREF="Ultra-DMA-10.html">Next</A>
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<A HREF="Ultra-DMA-8.html">Previous</A>
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<A HREF="Ultra-DMA.html#toc9">Contents</A>
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</BODY>
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</HTML>
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