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From: don311@gmx.us
To: linux-mtd@lists.infradead.org
Subject: jffs2, mtd, mtd-utils and ancient kernels
Date: Mon, 14 Oct 2019 20:01:03 -0500	[thread overview]
Message-ID: <1N9dsV-1hx2G70tCn-015aTM@mail.gmx.com> (raw)

Greetings,

I apologize for writing my first post here on a topic you've made
abundantly clear, for a long _long_ time now, that you have no interest
in: support for ancient kernels.  If it helps, let me be clear that I'm
not looking for "support" in quite the usual sense, but I have what I
think are a couple pretty basic questions.  I've tried downloading and
searching through the mailing list archives going back to the era that
the device I'm working on was originally developed (2004) without much
luck.  Google hasn't been much help with this either.  Of course it's
possible I just wasn't searching for the right things.

Basic questions:

Q1/ From what I've read, before MTD, JFFS2, and mtd-utils source code
    moved to Git in 2006, it was in CVS, and snapshots were available
    here:
        ftp://ftp.uk.linux.org/pub/people/dwmw2/mtd/...
    That doesn't seem to work any more (hardly surprising, I guess,
    after so long), but I'm wondering: Might those old snapshot archives
    still be available somewhere else?  I don't see any mention of it on
    the current web site.

Q2/ Is there anything you can point me to that shows which versions of
    MTD, JFFS2, and mtd-utils were delivered for use with each Linux
    kernel release?  In my case, I have particular interest in kernel
    2.4.26 -- so would it be possible to, say, find the mtd-utils
    version that corresponds to the version of MTD and JFFS2 used in
    2.4.26?

Slightly more detailed historical questions -- if any of you are still
reading, and happen to remember back that far:

Q3/ The JFFS2 code in 2.4 is referred to in several places (web site and
    mailing list) as stable, but does anyone here know/remember whether
    its "on-disc" (er, "on-flash") format continued to stay stable after
    2.4?  Put another way, how compatible (forwards and backwards) are
    JFFS2 images between 2.4 and later?
      - On the forward side, if one upgraded the kernel on a device that
        had been running 2.4.x (x >= 26) to something later, could the
        file system be used as-is?  (I mean, without risk of an ensuing
        mess?)
      - On the backward side, how dangerous would it be to use a 2.4.26
        kernel with a new (never mounted) JFFS2 image built with a later
        version of mkfs.jffs2?  (Not that one would deliberately choose
        such to do a thing, of course.)  I've built 2 or 3 different
        versions and found that they generate much different images from
        a constant "source" directory tree, but I haven't yet tried to
        dissect the images to understand the differences.

Q4/ The JFFS2 code in 2.4 is also referred to as well tested.  Is anyone
    here aware of whether that extends to the area of random hardware
    resets / power cuts, such as might be experienced on embedded
    devices without reliable power sources?  I see there were many
    performance improvements and bug fixes over the years, but are you
    aware of any data about relative reliability -- on the same hardware
    -- of JFFS2 in 2.4 vs much later / current, say?  (I believe "on the
    same hardware" would imply nor flash here, since 2.4 didn't support
    nand.)

I'd be happy to explain what sorts of colorful pharmaceuticals I've been
into that could cause me to ask such questions, but I suspect the above
may be enough flame-inducing stuff for one post.

Best regards,
Don

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             reply	other threads:[~2019-10-15  1:01 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-15  1:01 don311 [this message]
2019-10-15 19:11 ` jffs2, mtd, mtd-utils and ancient kernels Richard Weinberger
2019-10-16 20:27   ` don311

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