Date: Wed, 28 Nov 2001 11:11:55 -0800 From: Nick Pasich <npasich@crash.cts.com> To: "Justin T. Gibbs" <gibbs@btc.adaptec.com> Cc: Nick Pasich <npasich@crash.cts.com>, aic7xxx@FreeBSD.ORG Subject: Re: kernel panic with 29160 when doing tape backup Message-ID: <20011128111155.A16186@204.210.46.203> In-Reply-To: <200111261508.fAQF8RH17139@aslan.btc.adaptec.com>; from gibbs@btc.adaptec.com on Mon, Nov 26, 2001 at 08:08:27AM -0700 References: <20011120073136.A16255@204.210.46.203> <200111261508.fAQF8RH17139@aslan.btc.adaptec.com>
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On Mon, Nov 26, 2001 at 08:08:27AM -0700, Justin T. Gibbs wrote: > > The panic message: > > > > kernel panic: Too few segs for dma mapping. Increase AHC_NSEG > > > > > > I recompiled the kernel after increasing the AHC_NSEG's to 512 in > > aic7xxx_osm.h, but that didn't help. > > > > Not having a clue as to what the problem was, I started rebooting with > > older kernels. I tried 2.4.14-pre8, 2.4.13-ac4, 2.4.12-ac5 and > > 2.4.10-ac12. All of them gave the same panic message.... > > > > I finally tried 2.4.7, which gave me an error message, but completed > > the backup. > > > > The error message for 2.4.7: > > > > Saw underflow (4096 of 4096 bytes). Treated as error > > Saw underflow (4096 of 4096 bytes). Treated as error > > Saw underflow (4096 of 4096 bytes). Treated as error > > Saw underflow (4096 of 4096 bytes). Treated as error > > Saw underflow (4096 of 4096 bytes). Treated as error > > Saw underflow (4096 of 4096 bytes). Treated as error > > SCSI disk error : host 0 channel 0 id 0 lun 0 return code = 70000 > > I/O error: dev 08:01, sector 59591 > > I guess that the msdos file-system code in 2.4.7 does not have whatever > bug it is that causes the kernel to attempt an I/O that violates the > exported limit on the segment list set by the aic7xxx driver. If you > upgrade your 2.4.7 kernel to use the latest aic7xxx driver, you'll probably > have a stable system. Patches against 2.4.7 can be found here: > > http://people.FreeBSD.org/~gibbs/linux/ > > You might be able to track down the root cause of the bug by providing > a stack trace from the panic you see when dumping an msdos file system. > I guarantee you though, it is not the aic7xxx driver's fault. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > -- > Justin Justin, I have now upgraded to Linux Kernel version 2.4.16 and the same system lockup problem exists when doing a msdos partition backup to a scsi tape. The panic message: kernel panic: Too few segs for dma mapping. Increase AHC_NSEG I have another Linux Computer running the same kernel (2.4.16) that has no problems at all. The difference being the scsi adapter is a BusLogic Model BT-958 PCI Wide Ultra SCSI Host Adapter. I have replaced the contents of /usr/src/linux/drivers/scsi/aic7xxx directory (AIC7XXX_DRIVER_VERSION "6.2.4"), with the code from linux-2.4.7 (AIC7XXX_DRIVER_VERSION "6.1.13"). I now can now do a successful backup of an msdos partition with a couple of "kernel: Saw underflow (4096 of 4096 bytes). Treated as error" messages with no lockup. This is obviously a driver problem, as the only difference in the kernels is the code in the aic7xxx directory..... AIC7XXX_DRIVER_VERSION "6.2.4" causes kernel panic lockups.. AIC7XXX_DRIVER_VERSION "6.1.13" reports underflows and continues running.... If you have a msdos partition available, you might want to try a test backup to a scsi dat tape and see if you have the same problem....... Thanks for your time, ---( Nick Pasich )--- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message
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