Re: [dm-devel] [PATCH RFC v1 01/01] dm-lightnvm: An open FTL for open firmware SSDs

[Akira Hayakawa]

Hi, Matias,

Sorry for jumping in. I am interested in this new feature, too.

> > Does it even make sense to expose the underlying devices as block
> > devices?  It surely would help to send this together with a driver
> > that you plan to use it on top of.
> > 
> 
> Agree, an underlying driver is missing. My first plan is to get a draft
> firmware for the OpenSSD to be stable and expose its primitives
> (read/write/erase) up through the ATA/SCSI stack. Communicating using
> vendor specific codes.

Exposing FTL to the host layer has potential to share mapping in cache software (or driver) and the device.
The "Unified Address Space" in the slides below addresses the problem of two levels of indirection.
http://www1.unine.ch/eurosys2012/posters/saxena.pdf

Developing API to share mapping between driver and the device sounds interesting, too.

--
Akira
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