From: Boris Brezillon <boris.brezillon@bootlin.com>
To: xiaolei li <xiaolei.li@mediatek.com>
Cc: <richard@nod.at>, <linux-mediatek@lists.infradead.org>,
<linux-mtd@lists.infradead.org>, <srv_heupstream@mediatek.com>
Subject: Re: [PATCH] mtd: Add sysfs attribute for mtd OOB available size
Date: Tue, 3 Apr 2018 10:43:54 +0200 [thread overview]
Message-ID: <20180403104354.03895246@bbrezillon> (raw)
In-Reply-To: <1522723618.3504.7.camel@mhfsdcap03>
On Tue, 3 Apr 2018 10:46:58 +0800
xiaolei li <xiaolei.li@mediatek.com> wrote:
> Hello Boris,
>
> On Mon, 2018-04-02 at 14:15 +0200, Boris Brezillon wrote:
> > Hi Xiaolei,
> >
> > On Mon, 2 Apr 2018 16:20:10 +0800
> > Xiaolei Li <xiaolei.li@mediatek.com> wrote:
> >
> > > Expose mtd OOB available size by sysfs file. Then users can get available
> > > OOB size by accessing /sys/class/mtd/mtdX/oobavail.
> >
> > May I ask why you need to expose that? I'm not against exposing new
> > things through sysfs, but since this is part of the ABI, I'd like to be
> > sure we actually need it.
> >
> That is user-space can write OOB data through ioctl MEMWRITE now.
> If OOB operation mode is MTD_OPS_AUTO_OOB, user should know how many
> OOB available bytes it can use. But I didn't find a way to get it. (If
> there is already a method, please kindly let me know, thanks.)
Nope. We have the ECCGETLAYOUT ioctl, but it's not reliable because of
the MTD_MAX_OOBFREE_ENTRIES limitation.
>
> One problem I know is to do Jffs2 type flash erase using MTD user-space
> tool flash_erase. flash_erase tool will program "cleanmarker" into OOB
> free area, but it can not get OOB available size.
That's a good reason to expose this property indeed. Do you plan to fix
mtd-utils to use the sysfs value when it's available? Also, do we need
to expose the ECC/free layout as done with the
ECCGETLAYOUT/MEMGETOOBSEL ioctls?
next prev parent reply other threads:[~2018-04-03 8:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 8:20 [PATCH] Add sysfs attribute for mtd OOB available size Xiaolei Li
2018-04-02 8:20 ` [PATCH] mtd: " Xiaolei Li
2018-04-02 12:15 ` Boris Brezillon
2018-04-03 2:46 ` xiaolei li
2018-04-03 8:43 ` Boris Brezillon [this message]
2018-04-03 9:40 ` xiaolei li
2018-04-03 10:14 ` Boris Brezillon
2018-04-03 11:01 ` xiaolei li
2018-04-04 20:05 ` Boris Brezillon
2018-04-08 1:26 ` xiaolei li
2018-04-26 18:04 ` Boris Brezillon
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