On Mon 02 Aug 2021 at 13:21:22 +0200, Thomas Schmitt wrote: > Hi, > > Brian wrote: > > Isn't /dev/sg0 the block device? > > /dev/sgX are character devices. > > https://tldp.org/HOWTO/SCSI-Generic-HOWTO/intro.html > says > "The driver's purpose is to allow SCSI commands to be sent directly to > SCSI devices. [...] Various specialized applications for writing > CD-Rs and document scanning use the sg driver." > > This is still the case for optical drives (sr) and hard discs (sd) which get > an sg device file additionaly to their block device file. But it seems that > the statement about "document scanning" could need an update. > > > The main call for sg devices is ioclt(SG_IO) which performs a single SCSI > command transaction. > Since about 15 years it is possible to use it directly with a /dev/srX > device file. But a bug introduced in a late version of kernel 2.6 prevented > concurrent use of SG_IO on multiple sr devices. This ended with > https://github.com/torvalds/linux/commit/51a8588 > which i assume went into kernel version 5.6. > So with the currently released Debian versions, /dev/sgX is still of use > if there is more than one sr device.
I misread sr0 as sg0; sorry to have put you to the trouble of posting. On the bright side, you have helped clear up a misconception of mine. -- Brian.
