On Tue, 2006-11-14 at 11:02 +0900, Tejun Heo wrote: > Hello, Mattieu Fluhr. > > Mathieu Fluhr wrote: > > The problem is that, on SATA devices controlled by libata, on some big > > files (like for example a 600 MB file) the READ command seems to fail > > and outputs garbage (not 1 or 2 bytes diff, but the whole buffer). > > -> This problem does not come out everytime, and each time on > > different sectors. > > > > Please note that: > > - it is not chipset dependant (tested on nforce4 and sii3114) > > - it is not medium or device dependant > > Hmmm... Interesting. So, you're reading the media by directly issuing > commands through the sg interface, right? Can you please try the > followings? > > * Try using /dev/srX or /dev/scdX device instead of /dev/sgX. You can > use the command SG_IO but the code path is different, so it will help us > rule out sg bug. > > * Perform rounds of read-verify test using standard block interface (ie. > simply opening /dev/srX and reading it). I will try this and report the results. > > [--snip--] > > - When I force the bus type to be IDE, our software will then send ATA > > commands. In this case, everything works like a charm. No errors at all. > > What do you mean by 'sending ATA commands'? libata exports all devices > as SCSI devices. For ATA devices, you can use ATA passthrough but you > send CDBs to ATAPI devices anyway. Inside our code, we first guess which the bus type of every device using an INQUIRY cmd (0x12). - If the device appears to be a SCSI one, then we send "pure" SCSI CDBs - For an IDE device, we do, as described in the Annex A of the MMC-5 spec, and pad each CDBs to 12 bytes. So in the case of a READ CDB, we send 10 bytes if the device is a SCSI one and 12 for IDE one. > > Thanks. > - 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
