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Date:   Fri, 11 Nov 2022 00:39:15 +0000
From:   Daniel Golle <daniel@makrotopia.org>
To:     Richard Weinberger <richard@nod.at>
Cc:     Jens Axboe <axboe@kernel.dk>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Matthew Wilcox <willy@infradead.org>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Ming Lei <ming.lei@redhat.com>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-efi <linux-efi@vger.kernel.org>
Subject: Re: [PATCH v4 4/5] mtd_blkdevs: add option to enable scanning for
 partitions
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On Thu, Nov 10, 2022 at 09:12:35PM +0100, Richard Weinberger wrote:
> ----- Ursprüngliche Mail -----
> > On Thu, Nov 10, 2022 at 08:44:53PM +0100, Richard Weinberger wrote:
> >> ----- Ursprüngliche Mail -----
> >> > Von: "Daniel Golle" <daniel@makrotopia.org>
> >> > +
> >> > +		if (!IS_ENABLED(CONFIG_MTD_BLOCK_PARTITIONS) || mtd_type_is_nand(new->mtd))
> >> > +			gd->flags |= GENHD_FL_NO_PART;
> >> 
> >> I know that NAND should not get used with mtdblock because lack of wearleveling
> >> and
> >> in general too many writes. But what exactly is the rationale to deny part
> >> scanning for NAND?
> > 
> > As UBI should be used on NAND, partition scanning should be enabled for
> > ubiblock devices to have uImage.FIT filesystem subimages mapped by the
> > partition parser.
> > 
> > If not skipping partition scanning on NAND-backed mtdblock devices the
> > scanning itself will already trigger multiple warnings which now happen
> > every time when a NAND-backed mtdblock device is being opened since
> > commit 96a3295c ("mtdblock: warn if opened on NAND").
> 
> I see, you want to promote UBI. Makes sense.
> In case you do a v5 series, please add a comment to the code.

Will do, I'm planning to send v5 early next week.

If we are going to have only CONFIG_MTD_BLOCK_PARTITIONS and no other
config symbol for ubiblock devices I'd also merge the two patches for
mtdblock and ubiblock partition scanning into a single one.

Thank you for reviewing!


Daniel