Re: sg driver and Fedora Core 2

[Jeff Garzik <jgarzik@pobox.com>]

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.

	Jeff