linux-kernel - Re: [PATCH 3/4] mtd: mchp23k256: add partitioning support

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Message-ID: <20170601222320.GE102137@google.com>
Date:   Thu, 1 Jun 2017 15:23:20 -0700
From:   Brian Norris <computersforpeace@...il.com>
To:     Chris Packham <Chris.Packham@...iedtelesis.co.nz>
Cc:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>
Subject: Re: [PATCH 3/4] mtd: mchp23k256: add partitioning support

On Thu, Jun 01, 2017 at 09:30:07PM +0000, Chris Packham wrote:
> On 02/06/17 06:43, Brian Norris wrote:
> > On Wed, May 17, 2017 at 05:29:11PM +0200, Boris Brezillon wrote:
> >> Can we fix allocate_partition() to properly handle the
> >> master->erasesize == 0 case instead of doing that?
> >
> > Is everything actually ready for the eraseblock size to be 0?
> 
> That was my initial motivation for faking it.

Understood. I think it's probably better to avoid hacking drivers like
you were about to, but I was also curious if anyone had thought through
the implications of *not* forcing a non-zero size.

> > That would
> > seem surprising to many applications, I would think. Can you, for
> > instance, even use UBI on such a device?
> 
> I've tried ext2 and I believe Andrew has tried minix fs. We're talking 
> SRAM so UBI/UBIFS doesn't really provide much benefit for this use-case.

Right. But that's not necessarily true for all NO_ERASE devices, so we'd
probably want to think about that before allowing it.

Brian