Re: sg driver and Fedora Core 2

Jeff Garzik
2004-05-29T17:28:12Z

Really what needs to happen is a generic userland tap attaches to a
chrdev, issues an ioctl(2) to attach to a request_queue, and then does
read(2)/write(2)/mmap(2) to communicate with the request_queue.

:)

Call it /dev/bsg, or somesuch.

The SG_IO ioctl won't work for all cases, since some block devices may
rightly wish to limit (or block) multiple openers on the blkdev itself.
OTOH, the SG_IO ioctl does eliminate the userland app needing to
worry about _any_ target/addressing information, since that is implicit
in the dentry pointing to the blkdev's inode.

Jeff