Date: Thu, 18 May 2006 11:18:38 -0700 From: "marty fouts" <mf.danger@gmail.com> To: "Jim Thompson" <jim@netgate.com> Cc: gnn@freebsd.org, freebsd-small@freebsd.org Subject: Re: Flash File Systems or Translation Layers? Message-ID: <9f7850090605181118o30b71b94mca294b2195e9ae1e@mail.gmail.com> In-Reply-To: <2159F853-C89E-4032-9931-56F4B7D214C0@netgate.com> References: <m2bqtwoena.wl%gnn@neville-neil.com> <446BBE65.50104@FreeBSD.org> <9f7850090605171746p5ff4dbefq46211ce93aafc116@mail.gmail.com> <446C2380.6020000@FreeBSD.org> <A2451718-0B8F-4BF2-9466-F6EDC6DC212B@netgate.com> <9f7850090605181006m56c38a56lcc7037beaf6b6fa@mail.gmail.com> <2159F853-C89E-4032-9931-56F4B7D214C0@netgate.com>
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On 5/18/06, Jim Thompson <jim@netgate.com> wrote: > > On May 18, 2006, at 7:06 AM, marty fouts wrote: > > > On 5/18/06, Jim Thompson <jim@netgate.com> wrote: > >> > I have no idea how you got that impression, but ecos/redboot are at > least as "alive" as linux is, and more > popular than u-boot. (I had my mitts on u-boot back when it was > "ppcboot".) I was misinformed. Thanks for the correction. > >> Still having a bootloader that knows how to 'read' the filesystem > >> isn't that important, as long as you can store the kernel somewhere > >> other than >in< the filesystem. No "dinking" needed. (are you > >> aware that 'dink' is also a bootloader (for ppc)?) > > > > Agreed. This seems to be a common approach in shipping devices, and it > > has advantages that make it appealing. > > What is "this"? Sorry for the lack of clarity. Having the kernel somewhere other than in the filesystem is "this"; a common approach in shipping devices. > > This is why the authors were off designing JFFS3. Definitely > > investigate JFFS2, especially reading the archives of the MTD mailing > > list, but I'd strongly advise against modeling a system on its data > > structures. > In practice this is only a problem for systems with a >lot< of > flash. Most of the boards that are > interesting have 4-16MB of flash. None of the boards that are interesting to me have less than 64mb of flash ;) and I've seen JFFS2 performance problems on 16mb flash partitions. I'm coming at this from a telephony point of view, where none of the currently shipping devices are limited to 16MB of flash. 32mb is typical, 64mb is common, and 128mb development boards are in common use. (The TS7250 board that I mentioned earlier is available with 128mb NAND.) > I don't think we can restrict ourselves to supporting only NAND > flash. In particular, Intel's "Strataflash" (and the Micron (etc) > equivalents are all NOR-based. Agreed. But I think that NAND and NOR are enough different that they need to be supported differently.
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