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Date:   Fri, 23 Jul 2021 02:17:58 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Wedson Almeida Filho <wedsonaf@google.com>
Cc:     Finn Behrens <finn@kloenk.dev>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        rust-for-linux <rust-for-linux@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/17] Rust support
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On Thu, Jul 22, 2021 at 11:55:58PM +0100, Wedson Almeida Filho wrote:
> Hey Matthew,
> 
> On Thu, Jul 08, 2021 at 01:58:32AM +0100, Matthew Wilcox wrote:
> > Why are you so resistant to writing a real driver that deals with actual
> > hardware?  
> 
> I don't think it was so much resistance but rather a prioritisation thing. Have
> you by any chance seen the gpio driver I posted a couple of days ago?

I haven't seen it, no ...

> > 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.

As I said, they've put all kinds of crap into NVMe these days.
If you look at the 1.0e spec, it's 127 pages.

> 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?

Unfortunately, most of the early versions were lost during the
kernel.org breakin.  If you check out commit 5da273fe3fd1 and look at
drivers/block/nvme.c, you'll see a driver that's about 2000 lines.