David might be right in principle, but when component price matters, you have to buy the hardware that the mass market offers. Right now the sweet spot is "smart" devices with embedded Flash Translation Layer firmware. I'd place my bet on that trend continuing.
Linux does not "drive" the mass market. Asian volume manufacturers barely know what Linux is. Maybe that is changing, but there is a long way to go before the reality on the ground changes. David minimizes the impact of NAND geometry changes. The reality is that it doesn't have to change "that much" to "flip" the decision. We at OLPC tried in vain to find a way to get past 2 GiB with the internal NAND. The problem is that the controller hardware is coupled to the NAND technology (MLC vs SLC) and page size. The coupling is caused by the fact that the error correcting codes must be tuned to those factors. ECC for 2K-page SLC is just no good for 4K MLC. ECC generation and checking must be done in hardware for adequate performance. Our existing NAND controller just didn't work for the generation of chips that has largely supplanted the chips we were using. So get a new controller, right? Well, if you go and try to buy one, you will find that they all come with embedded microprocessors that implement a Flash Translation Layer, and the manufacturers closely guard the operational details. It would be nice if they would reveal their secrets so the FOSS community could write some "better" firmware for those controllers. Good luck making that happen. And good luck getting it deployed before the chip has been superseded. You might think that System on Chip devices for the embedded market might yield a different answer. That's not what we saw. Every time we looked at an SoC presentation, invariably the device did not have a suitable raw NAND controller. That is what started me to thinking that raw NAND was about to get killed in the market by "managed NAND". Everything these days has an SD controller or three. David is absolutely right that many of the current FTL-equipped devices are nearly hopeless. But that is not the same as saying that they all are. A few devices have done quite well in our stress testing. Over time, I expect the situation to get better and better as the firmware that "gets it right" supplants the earlier tries. _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
