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From:   "Alan C. Assis" <acassis@gmail.com>
Date:   Tue, 18 Jul 2023 10:04:55 -0300
Message-ID: <CAG4Y6eTN1XbZ_jAdX+t2mkEN=KoNOqprrCqtX0BVfaH6AxkdtQ@mail.gmail.com>
Subject: Re: File system robustness
To:     =?UTF-8?Q?Bj=C3=B8rn_Forsman?= <bjorn.forsman@gmail.com>
Cc:     Kai Tomerius <kai@tomerius.de>, linux-embedded@vger.kernel.org,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        dm-devel@redhat.com
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Hi Bj=C3=B8rn,

On 7/18/23, Bj=C3=B8rn Forsman <bjorn.forsman@gmail.com> wrote:
> On Tue, 18 Jul 2023 at 08:03, Kai Tomerius <kai@tomerius.de> wrote:
>> I should have mentioned that I'll have a large NAND flash, so ext4
>> might still be the file system of choice. The other ones you mentioned
>> are interesting to consider, but seem to be more fitting for a smaller
>> NOR flash.
>
> If you mean raw NAND flash I would think UBIFS is still the way to go?
> (It's been several years since I was into embedded Linux systems.)
>
> https://elinux.org/images/0/02/Filesystem_Considerations_for_Embedded_Dev=
ices.pdf
> is focused on eMMC/SD Cards, which have built-in controllers that
> enable them to present a block device interface, which is very unlike
> what raw NAND devices have.
>
> Please see https://www.kernel.org/doc/html/latest/filesystems/ubifs.html
> for more info.
>

You are right, for NAND there is an old (but gold) presentation here:

https://elinux.org/images/7/7e/ELC2009-FlashFS-Toshiba.pdf

UBIFS and YAFFS2 are the way to go.

But please note that YAFFS2 needs license payment for commercial
application (something that I only discovered recently when Xiaomi
integrated it into NuttX mainline, bad surprise).

BR,

Alan