Hi David, Thanks for the good info on wear levelling; apparently I was misinformed on the topic.
On Thu, 2016-06-16 at 01:03 -0700, David Lang wrote: [snip] > >>> To a certain extent though, I question the need for something as > >>> restricted as OpenWrt > >>> for the new bigger devices anyway; there are elements like netifd that > >>> would be good to > >>> see continue, but I'm not sure that most of OpenWrt really makes as much > >>> sense when you're > >>> not needing to squeeze maximum use out of very erase block, and that > >>> therefore, while it > >>> may be a smaller market/mindshare, that focussing on the the true > >>> embedded type scenario, > >>> seems to be more of what LEDE's niche is. > >> > >> LEDE/OpenWRT is a good fit for any device that operates on raw flash > >> instead of > >> a hard drive or ssd with wear leveling. Once you have storage that you > >> don't > >> worry about wearing out and is large enough to hold a normal Linux Distro, > >> it > > > > makes sense to move to such a distro and update packages individually. > > > > Hmmm...the wear levelling thing is confusing. I was told by someone who I > > thought knew > > what they were talking about, that flash chips included some form of > > hardware-based > > wear levelling built in already. Apparently that is was inaccurate > > (hardware-level > > support is something I only having minor knowledge of; it's not the part > > the interests me, > > nor where I have worked on it for any length of time; I'm more interested > > in what you can > > do with existing hardware support combined with software rather developing > > the core support > > itself). > > raw flash chips like we have in a router have nothing. > > flash chips packaged in SD cards, USB drives, etc commonly have very > primitive > wear leveling (in many cases only targeted at the places that the FAT > filesystem > is going to use) > > flash chips packaged into SSD drives or anything more sophisticated tend to > have > very extensive wear leveling setups, and will move existing, unmodified data > if > needed to balance things. > > I haven't looked recently, but a couple years ago the idea of having an > in-kernel flash wear leveling capability was getting a lot of discussion on > the > kernel mailing list. I din't remember seeing what finally happened with that. > > For the very tiny devices, it doesn't make sense to try and make use of > something like that (it takes more space ond isn't going to apply to a > static, > pre-build compressed filesystem) > > But for the overlay filesystem where new stuff may get added on newer devices > that have the much larger NAND flash, it may be something to look into, even > though it complicates the base config for such systems. > Okay, I understand a lot better where you are coming from now, since I was under a misapprehension about the capabilities of the hardware. In this case I agree we need to do some work to support these bigger devices including things like wear-levelling, and that this is definitely a space in which LEDE can be relevant going forward. Regards, Daniel _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
