Red Hat Bugzilla – Bug 128826
errors in read with cdrom scsi emulation
Last modified: 2007-11-30 17:10:46 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040619 Description of problem: Using dd to verify burned ISO image fails using scsi emulation layer, but passes using straight atapi (not using hdc=ide-scsi on grub boot line). This example is from disc 4 of FC2 release. Disc is verified good on another computer. $ dd if=/dev/scd0 bs=2k count=99481 | md5sum scsi0: ERROR on channel 0, id 0, lun 0, CDB: Read (10) 00 00 01 84 64 00 00 37 00 current sd0b:00: sense key Medium error Additional sense indicates L-EC uncorrectable error I/O error: dev 0b:00, sector 397712 dd: reading '/dev/scd0', Input/output error 99428+0 records in 99428+0 records out ------- reboot without ide-scsi -------------- $ dd if=/dev/hdc bs=2k count=99481 | md5sum (returns correct result) ------ from dmesg --------------- Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4 ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx ICH4: IDE controller at PCI slot 00:1f.1 PCI: Found IRQ 9 for device 00:1f.1 PCI: Sharing IRQ 9 with 00:1d.2 ICH4: chipset revision 1 ICH4: not 100% native mode: will probe irqs later ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, hdb:pio ide1: BM-DMA at 0xffa8-0xffaf, BIOS settings: hdc:DMA, hdd:pio hda: ST380011A, ATA DISK drive blk: queue c0402f40, I/O limit 4095Mb (mask 0xffffffff) hdc: SAMSUNG CD-R/RW SW-252S, ATAPI CD/DVD-ROM drive ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 ide1 at 0x170-0x177,0x376 on irq 15 hda: attached ide-disk driver. hda: host protected area => 1 hda: 156250000 sectors (80000 MB) w/2048KiB Cache, CHS=9726/255/63, UDMA(100) Partition check: hda: hda1 hda2 hda3 hda4 < hda5 hda6 hda7 hda8 hda9 > ide: late registration of driver. ... SCSI subsystem driver Revision: 1.00 hdc: attached ide-scsi driver. scsi0 : SCSI host adapter emulation for IDE ATAPI devices Vendor: SAMSUNG Model: CD-R/RW SW-252S Rev: R902 Type: CD-ROM ANSI SCSI revision: 02 -------- from lspci -v -------- 00:1f.1 IDE interface: Intel Corp. 82801DB (ICH4) Ultra ATA 100 Storage Controller (rev 01) (prog-if 8a [Master SecP PriP]) Subsystem: Dell Computer Corporation: Unknown device 0160 Flags: bus master, medium devsel, latency 0, IRQ 9 I/O ports at <ignored> I/O ports at <ignored> I/O ports at <ignored> I/O ports at <ignored> I/O ports at ffa0 [size=16] Memory at feb7fc00 (32-bit, non-prefetchable) [size=1K] Version-Release number of selected component (if applicable): kernel-2.4.22-1.2197.nptl How reproducible: Always Steps to Reproduce: 1. burn CD with binary disc 4 image from FC2 release 2. $ dd if=/dev/cdrom bs=2k count=99481 | md5sum 3. note error messages 4. reboot system without hdc=ide-scsi boot option 5. $ dd if=/dev/hdc bs=2k count=99481 | md5sum 6. note no errors and correct MD5SUM reported Actual Results: read errors reported from dd Expected Results: no read errors from dd Additional info:
I can't seem to get Bugzilla to change my e-mail address. Use fedora@berkshirecycling.org to contact me.
Created attachment 103497 [details] script to show read beyond end of device This script will show that kernel will attempt to read more blocks than requested by dd. The attempt to read beyond the end of the device reports an error, causing dd to fail. This appears to happen only with images that have an odd nubmer of 2k byte blocks. Is ide-scsi layer trying to use 4k blocks or do a read-ahead beyond end of device? This behavior does not occur using basic IDE device (/dev/hdd rather than /dev/scd1).
The medium errors reported above *might* be due to a bad drive. I installed another drive and don't get them. I'm still not sure, as the errors do not appear using /dev/hdX rather than /dev/scdX. There is definitely a repeatable problem with verifying CD images that have an odd number of 2k byte blocks. (e.g. discs 2 and 4 of the Fedora Core 2 distribution, which caused a great deal of trouble for me) Kernel message showing read attempt beyond end of dd request (dd if=/dev/scd1 bs=2k count=12345): Sep 5 22:33:12 spike kernel: I/O error: dev 0b:01, sector 49380 Sep 5 22:33:12 spike kernel: attempt to access beyond end of device Sep 5 22:33:12 spike kernel: 0b:01: rw=0, want=24692, limit=24690 version info: kernel-2.4.22-1.2199.nptl cdrecord-2.01-0.a19.2
This read beyond end of device also occurs using vanilla 2.4.27 kernel.
Thanks for the bug report. However, Red Hat no longer maintains this version of the product. Please upgrade to the latest version and open a new bug if the problem persists. The Fedora Legacy project (http://fedoralegacy.org/) maintains some older releases, and if you believe this bug is interesting to them, please report the problem in the bug tracker at: http://bugzilla.fedora.us/