Re: [PATCH] bsg : Add support for io vectors in bsg

[Mark Rustad]

On Jan 10, 2008, at 3:46 PM, Pete Wyckoff wrote:

> I'm fine with read/write, except Tomo is against handling iovecs
> because of the compat complexity with struct iovec being different
> on 32- vs 64-bit.  There is a standard way to do "compat" ioctl that
> hides this handling in a different file (not bsg.c), which is the
> only reason I'm even considering these ioctls.  I don't care about
> compat setups per se.

That is what I was thinking. Is it really necessary to support  
something like bsg for 32 on 64 bit? Yes, it is a userspace interface,  
but it isn't the kind of thing that normal user programs would use. It  
is a new interface for newly-written programs and I would expect those  
to be native. At least it doesn't strike me as overly-restrictive for  
that to be the case for this kind of interface.

> Is there another async I/O mechanism?  Userspace builds the CDBs,
> just needs some way to drop them in SCSI ML.  BSG is almost perfect
> for this, but doesn't do iovec, leading to lots of memcpy.


Precisely.

--
Mark Rustad, MRustad@xxxxxxxxx


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