Re: sg driver and Fedora Core 2

[Jens Axboe <axboe@suse.de>]

On Sat, May 29 2004, Jeff Garzik wrote:
> James Bottomley wrote:
> >On Sat, 2004-05-29 at 12:27, Jeff Garzik wrote:
> >
> >>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.
> >
> >
> >Well, this touches on something else I'm thinking about: lazy
> >attachment.  In multi thousand disc environments, you don't want us
> >wasting resources allocating a queue and reading a partition table for
> >all of them; you really only want to do that for the devices you're
> >actually going to use.  Once we have this, I think dual attachment will
> >be a dead issue.
> 
> 
> Regardless of lazy attachment, request_queues need to support multiple 
> simultaneous producers of struct request's.

That has always been the case, even if it was just driver private use
before. As such there is no dual-attachment issue for sg.

-- 
Jens Axboe