[Stgt-devel] User-mode iSER

[FUJITA Tomonori]

From: Tom Tucker <tom at opengridcomputing.com>
Subject: Re: [Stgt-devel] User-mode iSER
Date: Tue, 01 Aug 2006 15:43:09 -0500

> > and it will be better if kernel/user space line is marked. so people
> > know your intention and can comment in that if need. otherwise, i saw no
> > difference from stgt or scst.
> 
> Attaches is a new picture with kernel/user boundaries. I think the
> boundary is somewhat fuzzy at the top and bottom due to the fact that
> the API is different for each target type and for each network provider
> type. 
> 
> For example, the sd driver will use open /dev/sdN and submit ioctl to
> read/write the disk, whereas the file target will
> open("/home/thisandthat", ...) and submit lseek/read/write to read/write
> the file.
> 
> On the network side, the TCP provider would use socket, listen, accept,
> send, recv (at least initially), the RMDA provider would use
> rdma_resolve_addr, rdma_resolve_route, rdma_listen, rdma_accept,
> rdma_create_qp, rdma_post_send, etc....
> 
> My only point is that the kernel/user interface is not a straight line
> since some of these interfaces are higher level than others.

Yes. Most of the tgt drivers (except for iSCSI tcp and iSER drivers)
need their own in-kernel part. Oh, iSCSI hardware drivers (like
qla4xxx) need the in-kernel part too.