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Date:   Fri, 2 Nov 2018 14:14:44 -0700
From:   Daniel Walker <danielwa@cisco.com>
To:     Richard Weinberger <richard.weinberger@gmail.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>, nkela@cisco.com,
        xe-linux-external@cisco.com, LKML <linux-kernel@vger.kernel.org>,
        "linux-mtd @ lists . infradead . org" <linux-mtd@lists.infradead.org>,
        Rod Whitby <rod@whitby.id.au>,
        David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH] Make JFFS2 endianness configurable
Message-ID: <20181102211444.nqqqbd4w5diyqrfw@zorba>
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On Fri, Nov 02, 2018 at 09:15:06PM +0100, Richard Weinberger wrote:
> On Fri, Nov 2, 2018 at 3:04 PM Daniel Walker <danielwa@cisco.com> wrote:
> > Do you have any thought on how to implement it ? I was think abstracting the
> > endian functions in the nodelist.h
> 
> Yes, see what UFS does.
> 
> > static inline jint16_t cpu_to_je16(jint16_t x) {
> >         if (check_big_endian()) {
> >                 return cpu_to_be16(x);
> >         } else if (check_little_endian()) {
> >                 return cpu_to_le16(x);
> >         }
> > }
> >
> > but how would you setup the checking ?
> 
> Make it a mount option and store the endianness mode in the super block.

It's actually a mkfs option currently. I'm not sure how that factors in,

from the mkfs.jffs2 man page,

       -l, --little-endian
              Create a little-endian JFFS2 image.  Default is to make an image with the same endianness as the host.

       -b, --big-endian
              Create a big-endian JFFS2 image.  Default is to make an image with the same endianness as the host.


Daniel