From: Richard Weinberger <richard@nod.at>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Vignesh Raghavendra <vigneshr@ti.com>,
Boris Brezillon <boris.brezillon@collabora.com>,
Ron Minnich <rminnich@google.com>, sven <sven@narfation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mtd <linux-mtd@lists.infradead.org>,
fuse-devel <fuse-devel@lists.sourceforge.net>
Subject: Re: [PATCH 0/8] MUSE: Userspace backed MTD v3
Date: Wed, 10 Feb 2021 12:23:53 +0100 (CET) [thread overview]
Message-ID: <1183985773.380599.1612956233979.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <20210210121429.4fb5ecf3@xps13>
Miquel,
----- Ursprüngliche Mail -----
>> Does in-band and OOB data need to be handled together?
>
> Short answer: yes.
>
>> If so, then two requests is not a good option.
>
> More detailed answer:
>
> There is a type of MTD device (NAND devices) which are composed, for
> each page, of X in-band bytes plus Y out-of-band metadata bytes.
>
> Accessing either the in-band data, or the out-of-band data, or both at
> the same time are all valid use cases.
>
> * Read operation details:
> From a hardware point of view, the out-of-band data is (almost)
> always retrieved when the in-band data is read because it contains
> meta-data used to correct eventual bitflips. In this case, if both
> areas are requested, it is highly non-efficient to do two requests,
> that's why the MTD core allows to do both at the same time.
> * Write operation details:
> Even worse, in the write case, you *must* write both at the same
> time. It is physically impossible to do one after the other (still
> with actual hardware, of course).
>
> That is why it is preferable that MUSE will be able to access both in
> a single request.
By single request we meant FUSE op-codes. The NAND simulator in Userspace
will see just one call. My plan is to abstract it in libfuse.
Thanks,
//richard
next prev parent reply other threads:[~2021-02-10 11:32 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-24 23:19 [PATCH 0/8] MUSE: Userspace backed MTD v3 Richard Weinberger
2021-01-24 23:20 ` [PATCH 1/8] fuse: Export fuse_simple_request Richard Weinberger
2021-01-24 23:20 ` [PATCH 2/8] fuse: Export IO helpers Richard Weinberger
2021-01-24 23:20 ` [PATCH 3/8] fuse: Make cuse_parse_one a common helper Richard Weinberger
2021-01-24 23:20 ` [PATCH 4/8] mtd: Add MTD_MUSE flag Richard Weinberger
2021-01-24 23:20 ` [PATCH 5/8] mtd: Allow passing a custom cmdline to cmdline line parser Richard Weinberger
2021-01-24 23:20 ` [PATCH 6/8] fuse: Add MUSE specific defines FUSE interface Richard Weinberger
2021-01-24 23:20 ` [PATCH 7/8] fuse: Implement MUSE - MTD in userspace Richard Weinberger
2021-01-24 23:20 ` [PATCH 8/8] MAINTAINERS: Add entry for MUSE Richard Weinberger
2021-01-28 10:30 ` [PATCH 0/8] MUSE: Userspace backed MTD v3 Miquel Raynal
2021-02-01 13:14 ` Richard Weinberger
2021-02-01 13:55 ` Miklos Szeredi
2021-02-09 14:26 ` Miklos Szeredi
2021-02-09 14:35 ` Richard Weinberger
2021-02-09 15:10 ` [fuse-devel] " Luca Risolia
2021-02-09 15:22 ` Miklos Szeredi
2021-02-09 15:41 ` Richard Weinberger
2021-02-09 15:56 ` Luca Risolia
2021-02-09 16:04 ` Richard Weinberger
2021-02-09 16:28 ` Luca Risolia
2021-02-09 16:29 ` Richard Weinberger
2021-02-09 16:42 ` Luca Risolia
2021-02-09 16:50 ` Richard Weinberger
2021-02-09 17:46 ` Luca Risolia
2021-02-09 19:42 ` Miklos Szeredi
2021-02-09 20:06 ` Richard Weinberger
2021-02-10 10:12 ` Miklos Szeredi
2021-02-10 11:12 ` Richard Weinberger
2021-02-10 11:16 ` Miklos Szeredi
2021-02-11 18:09 ` Miklos Szeredi
2021-04-13 12:59 ` Miklos Szeredi
2021-02-09 21:39 ` Richard Weinberger
2021-02-10 10:16 ` Miklos Szeredi
2021-02-10 11:00 ` Richard Weinberger
2021-02-10 11:14 ` Miquel Raynal
2021-02-10 11:23 ` Richard Weinberger [this message]
2021-02-10 20:55 ` Miquel Raynal
2021-02-10 21:11 ` Richard Weinberger
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