From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 3 Jan 2001 07:12:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 3 Jan 2001 07:12:22 -0500 Received: from smtp1.mail.yahoo.com ([128.11.69.60]:41489 "HELO smtp1.mail.yahoo.com") by vger.kernel.org with SMTP id ; Wed, 3 Jan 2001 07:12:08 -0500 X-Apparently-From: From: quintaq@yahoo.co.uk To: linux-kernel@vger.kernel.org Subject: Fw: UDMA on 815e chipset X-Mailer: Sylpheed version 0.4.9 (GTK+ 1.2.8; Linux 2.2.16; i686) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20010103121218Z130812-439+8159@vger.kernel.org> Date: Wed, 3 Jan 2001 07:12:08 -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Greetings Gurus, Have I found a tiny, perhaps irrelevant, bug ? I have recently installed SuSE 7.0 with the supplied 2.2.16 kernel on my homebuilt dual-boot machine, which has an 815e chipset (Asus CuSL2 board), plus 30GB IBM Deskstar 75GXP HDD (hda). As I understand it both of these support UDMA modes4 and 5 / ATA 66 and 100. The bios will not allow UDMA mode 5 to be set unless the correct cable is detected. At boot-time under Windows the bios reports that UDMA Mode 5 has been set. I decided to tweak the HDD performance under linux. I began with ATA 33 by adding the following to my boot.local : /sbin/hdparm -c1 -m16 -d1 -X66 /dev/hda This line causes no problems and hparm reports UDMA mode 2 set with cache reads at 139.13 MB/sec and disk reads at 12.87 MB/sec. I then try increasing to ATA 66 by substituting -X68 for X66. At linux boot-time I now see that XF68 has been set, but then I see the error message : "ide0: speed warning UDMA /3/4/5 is not functional". As I understand it, this means that the kernel has tested for the correct cable, but sees a negative response. Even though I see the error message, I think that UDMA 4 / ATA 66 must actually have been set, because hdparm now reports cache reads at 143.82 MB/sec and disk reads at 15.76 MB/Ssec. hdparm also reports that the HDD is in UDMA mode 4. Much the same thing happens if I try for ATA 100 / UDMA 5 by substituting -X69. hdparm now reports that the drive is in UDMA mode 5, but I do not see any improvement in transfer speeds, from which I assume that my kernel cannot go higher than ATA 66. I assume (unwisely ?), from all this that for some reason the kernel's check for the correct UDMA cabling on this chipset / motherboard is failing, but that it is actually succeding in setting UDMA mode 5 and is happily running at ATA 66. Hence my "possibly irrelevant" bug report. I have carried out all of the tests I mention above with a substitute cable, but the results are the same. I have not (yet) suffered any loss of data or other problems by ignoring the speed warning. I am not subscribed to this list (perhaps I have revealed enough ignorance above to explain why not), but I do not know where else I should report the "problem", or where else I might get some feedback. If anyone can be bothered to respond, then I would be very grateful if you could CC the reply to me. Thanks Geoff "Scattered we were when the long night was breaking: But in bright morning converse again" _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/