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Wed, 16 Oct 2019 15:27:03 -0500 Date: Wed, 16 Oct 2019 15:27:03 -0500 To: Richard Weinberger From: don311@gmx.us Subject: Re: jffs2, mtd, mtd-utils and ancient kernels References: <1N9dsV-1hx2G70tCn-015aTM@mail.gmx.com> In-Reply-To: Message-ID: <1Mr9Bk-1hffmW1bPS-00oJde@mail.gmx.com> X-Provags-ID: V03:K1:sy99KWGIHC7fQJKp4i4K8gxSSUHQc7Z52BTr7EX2ODD7meDZUdV 0jgbJS1PlW+VfFz2kLSEumErUVS49ZxV3WsjR6GMlWEhRZ5/hJgXPIXMCX2vqX2lyvu1aZc w68kJKtlkMuqYQFIY90h8TNkF9U0IAL+zR587DudqVtwN5kpa0WyDkhTYz7yUm75ja3+KcJ oJzxlKSfp2Gj3KNlnkDUQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:oYwZ8wOFF4w=:PHzTgMvnGBKyvIpJoyDMuD NEwFef5qrgJvDtjv+KTzkkKpdIrwH+Rn5HfdqzKnrz7pMi3vElJwKxDwVQIXuS5ft8+uenayi p+/L3A4Yp+QwQ4g5udoFs2eMQoMLXwkD4WnAd8cZa+Y8T9DstftD1bjew0c1EdGHrceF7RtOb dLa2fCbLFSTBQd53M66ccI3y97gofJ7Q9VtCs9ghZS23iLBS6+UjXmcp+t4FJHS6S2Zo48m3T gpuVLksKH/kWipCLYXftt+6Ppa4gdBqYN3Qp29T5/C+qoCwChJY2hpPtZ2B/TbMjt2Ti5RKqq oi0Z6gE1poJIbiy3QatEEmMSPXcz22QnB8Y9nrGRMkBxCoojCmjtG4aiV6xnSIdiMlW/IP5pH q6E7IB532cFfb233tyA3pBGBK64dMs2IlyI1I7Ozlo9Hsr0gMUSaNW1cChXwbMJXHMpODyUdO IOnTD147MH5DELgxwVm3FdQzgQY6JNcAH4LZWE/fQbeLzwhrFnSrUPxt+9nepOSeZKbcemAPy fomMPOTrAL9tLVgbxRnJIPpc7ScIB5mEqABOhiITyFzVBxeP27F0MI3bQrONi142IRlbKWfS/ FYO6+bDVJRJa5GJ8gkyG02bUaMacwB6pAZgE76d515FNC7HaZ0gMRUI99jhSeQgsx6mVg8HNL TlLX939Az6WxU7JmUyxbLN9LkEp19XUAEWeuX/IaPNp39dmrPRIRhRy8W6nXist5Isa3ebgyH byxBqqt4QLs0JYZAPDlgHDQQNTnzSDaXfX1lEaiKyXJHKn1xYdGawdvhkXozJZiFCqa1ZZ7pa Yr1AOJxB312zeGsNksFQK9mnCkCiQEUMT35fzORC+SqeC8jpp2TJtKn9ZkPdR5o/0TEoMHJUe 3Ou3Jjh6qzvoYfi8k3arOs1SbWEKO5WTKcGNywDg+9HHRQ2+/bld16PIgLPjsxUgmk2j+Tn+t X5FuT947M2IMrWXSUFzUQzt9VGEZTS+d0O/soHEL6U3jra107jxdpi8IzJ7WvtYONQf1aYpDC Dm2Nrad+NcdBPOIO+4k60lCrn6urBK/weKq1Erp7cExr9z5DR++C+l15FbB67x5k+hHkBDmKS zv2M/Ha+/0yannedkVZ/FdXiQRz4buOuGYQUumbIRX4KLtTZiDLHkACITlE7ftRB0HT792Jzg islVS9tnlyUA43llgXi8kiFUkQdoZbTBWsMAH03cbWwHhqJjubff74+H6ZFCaYQAW30CtvNFq u9Z8cXN579a+LEShoWjXmgZZE6QCruaAwvGFOQQ== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191016_132710_678069_672EC4EB X-CRM114-Status: GOOD ( 21.54 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mtd@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Tue, 2019-10-15 21:11:39 +0200, Richard Weinberger wrote: > On Tue, Oct 15, 2019 at 3:01 AM wrote: > > 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? > > Usually Debian is a good source for such an information. > ...or any other Linux distro with long term archives. Ah, good idea, I should've thought of this. They don't make the old stuff real easy to find, but it looks as though Debian jumped from mtd-tools 20011217-3 in 3.0 (Woody) to 20050122-2 in 3.1 (Sarge) -- quite a big jump. I also tried Fedora and couple distros that targeted embedded systems without much luck. But I can keep looking. I just noticed that one of the versions in our source repo is referred to as 20040219. That's plausible, considering 2.4.26 was released a couple months after that. Still, it would be nice to be able to verify that the code there matches the original release. > > - 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? ... > > As long you don't enable newer features in mkfs, it should work too. Okay, this is the situation I inherited: JFFS2 images that were generated with mkfs.jffs2 from ~2012 are being used in production with target systems running 2.4.26. To me it was a potential "red flag" from the start (without knowing any internal details), and discovering that image files generated by differing versions didn't match didn't make me feel any better about it. But I'm glad to hear there are no obvious incompatibilities. I'll have to check the command line, but I doubt we're using any newer features. > > 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.) > > You *really* don't want to use a 2.4 kernel. Very true! :-) The device I've been hired to work on is used in the building automation and HVAC industries, where support cycles can run decades, rather than years (or months) as in many other fields. Some of the issues I've fixed have been within the client's own software, but some have been in the platform -- in custom hardware drivers, for example. Each one comes with some sort of calculation of cost (typically my time) and risk, compared to expected benefit in the field. In this case, I discovered that a relatively high proportion of defective units returned from customer sites (that were attributable to failures in this part of the system) have moderate to severe file system corruption. There are many possible explanations, but one of my theories about it is unfortunate timing of power cuts, relative to file writes or garbage collection, say. If this was a known vulnerability of the otherwise "stable" 2.4 JFFS code, dealing with that would be a high priority; if not, I'd look elsewhere first. Moving to a modern kernel, while _very_ appealing in so many ways, is probably not something that the client would buy into for this long-obsolete (development-wise) product -- at least not without that cost-benefit calculation showing that it's an overall win. I'm not even sure the core hardware is still supported with modern Linuxes and toolchains. So the "pharma" involved here is kind of related to my salary. :-) Best regards, Don Estabrook ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/