Re: [PATCH 00/17] Rust support

Keith Busch
2021-07-23T15:08:10Z

On Thu, Jul 22, 2021 at 11:55:58PM +0100, Wedson Almeida Filho wrote:
> On Thu, Jul 08, 2021 at 01:58:32AM +0100, Matthew Wilcox wrote:
> > A simple NVMe driver is less than a thousand lines of C.
> > I know the one in the kernel now is ridiculously complicated and has
> > been thoroughly messed up with abstractions to support NVMeoF instead
> > of having a separate driver, but it's really a simple interface at heart.
>
> The latest NVMe spec is 452 pages long, which seems to contradict your claim
> that it's simple. In any case, translating less than 1K lines of C shouldn't be
> too hard (after I've built the abstractions, of course). Would you mind sharing
> the simple driver you mention above?

You can use the 1.0 spec, which is much shorter. A 1.0 capable driver
should be forward compatible with newer devices, too.

The current nvme driver became less simple since blk-mq integration and
has only gotten more complicated since then with other transports and
more advanced features. For a simpler example, you can reference an in
kernel version <= 3.16, and ignore the "nvme-scsi" parts.