It looks like both LIBATA and the old IDE drivers have an off-by-one error in deciding whether to use READ SECTOR(S) instead of READ SECTOR(S) EXT. Sorry the kernel numbers are in the range around 2.6.24. Knoppix 6.0.1 has a newer kernel but doesn't have hdparm, so I haven't tested it yet. Also this adds onto a thread that I started in linux-kernel yesterday, but a lot of information here is new. LBA number 0x0fffffff fits in 28 bits but READ SECTOR(S) can't reliably handle it. In my testing the largest LBA number that could be read reliably using READ SECTOR(S) is 0x0ffffffe. It looks like a Western Digital drive could handle sector number 0x0fffffff in LBA28, but Toshiba and Seagate couldn't. This can be reproduced using commands hdparm --read-sector 268435455 /dev/sda or hdparm --read-sector 268435455 /dev/hda depending on which driver is involved. Sectors 268435454 and 268435456 have no problem. I didn't take a close look but a pretty obvious guess is that LBA28 worked for the preceding one and LBA48 worked for the following one. If LIBATA is in charge, dmesg shows that the command was 0x20 (READ SECTOR) and the sector number appears to be correct, but the error bit is IDNF. If IDE is in charge, dmesg shows that the command was 0x20 (READ SECTOR) and the sector number is shown as 16777215 instead of 268435455. This looks like an error in the error message to compound the error in the main code. I'll guess the command had the additional nibble correct, just that LBA28 can't handle it. Sometimes the dd command can read that sector but sometimes not. If dd fails then dmesg shows several error messages with sector numbers, 0x0ffffff8, 268435448, and 33554431. Someone decides 8 sectors should be read so the start sector makes sense in both hex and decimal, but the error sector is missing three bits instead of missing an entire nibble. And here, the command code is 0xc8, READ DMA, LBA28 again. This one needs changing to READ DMA EXT. All drives in my test were SATA, and the chipsets were ICH7 or ICH7M, but BIOSes differed in setting ICH7 to expose IDE or SATA interfaces. In the case with ICH7 and full SATA operation, the Western Digital drive worked but Seagate failed. -------------------------------------- Power up the Internet with Yahoo! Toolbar. http://pr.mail.yahoo.co.jp/toolbar/ -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
