Posted by planetbeing on under iphe, realiti, comex, obama, oses, worst case, sdk, voodoo, kernel, presidency, sectors, samsung, linux, map | 
So the big news yesterday (other than Obama winning the presidency!) is that we have enough of a low-level NAND driver now that we're able to read from NAND! It was epic win. There turns out to be not as much hardware voodoo as, say, Merlot, so that's pretty good news. It seems to work (albeit slowly) and I even wrote the ECC routines today (and those seem to work as well).
Unfortunately, in the course of this, we discovered several unfortunate things. First, I can't seem to find anything that might write to NAND. It's probably not much more complicated and probably reuses a lot of the stuff we've been doing, but it means that we might have to look in the kernel for that code, which sort of bites (a lot of the kernel is in C++ and not as friendly to reverse).
The second thing is the realization that all of Samsung's proprietary FTL code is in this thing. Without being able to understand it, we can't actually map sectors to data and we can't make sense of the NAND data or write new data to it in a useful way. Unfortunately, this code is liable to be ridiculously complex, since it's basically their SDK they ship to everyone. Without it, we can still proceed, but the iPhone can't read Linux's data and Linux can't read iPhone's data. In the worst case, we can't even have both OSes on the NAND at once.
Still, being able to dump NAND through USB is a substantial accomplishment, and we're well on our way.
Tagi: iphe, realiti, comex, obama, oses, worst case, sdk, voodoo, kernel, presidency, sectors, samsung, linux, map
Posted by planetbeing on under raw hardware, e care, bad blocks, locati, ftl, data structures, slew, gadget, amount of time, algorithms, kernel, sectors, ace, yaffs, proposal, benefit, linux |
We've made some progress on the USB gadget driver for Linux, and we're now running a generic serial gadget for communication. This implementation is important because USB is now a lot less laggy and things like ethernet over USB, etc., can eventually be supported, easing access.
We've also got pretty far with porting the NAND driver to Linux. Most of the read support is now there, and we've isolated the routines in the iPhone kernel where the raw hardware write occurs. CPICH and c1de0x are working on reversing it. Hopefully, it will be analogous enough to reads that it won't take a huge amount of time to work out.
This is different from reversing their FTL, however, which is a complicated slew of data structures, merge buffers and other exotic algorithms that take care of evenly distributing writes throughout the device and also making writes take less time.
I think reversing all of that would take too much time and effort. Instead, my proposal is to just reverse the hardware NAND writes. Instead of using a partition, we would have a loop-mounted root filesystem (similar to how Wubi is setup), with the root filesystem being a file on the Media partition. Since there's a non-empty file at that location, the FTL system, whatever it is, must create a one-to-one mapping from logical sectors to physical NAND pages. We can already read the mapping it creates (we have already reversed the read-side FTL code), and so all we have to do to alter the data is to write to the same pages we would've read from. Of course, this means that wear-leveling and bad block handling is not performed. However, if we use a filesystem that's aware of bad blocks and can wear-level (YAFFS or JFFS2), then it amounts to the same thing. The wear-leveling would then take place over the particular physical pages belonging to the rootfs image, rather than the entirety of the NAND. This would make the physical pages belonging to the rootfs image wear out a little faster than the rest of the NAND, but the actual effect of this should be inconsequential.
The additional benefit of this setup is that there's no repartitioning required, so setup is cinch. See
this wiki document for specific proposed implementation details.
Tagi: raw hardware, e care, bad blocks, locati, ftl, data structures, slew, gadget, amount of time, algorithms, kernel, sectors, ace, yaffs, proposal, benefit, linux
Posted by on under pig face, paw print, dney, kirf, rear speakers, camera light, maced, phe, jaunt, extreme cases, smattering, clamshell, butts, gadget, hg, kitty, sectors, gadgets, mobile phone, nbsp |
Oh China, how we love the gadgets you produce. Particularly those of the
homegrown variety. We can't say we spotted this pig face mobile during our
recent jaunt through the gadget sectors of Hong Kong, but boy, do we wish we had. In one of the most extreme cases of product confusion
ever, it looks as if we've got a clamshell phone with the face of a pig, a 0.3 megapixel camera, light-up eyes, a smattering of misplaced Walt Disney logos, paw print send / end buttons and rear speakers, and a random Winnie the Pooh sticker on the rear -- you know, to really cap things off. We're guessing this is some failed attempt to generate yet another
KIRF Disney phone, but seriously, a glowing pig?
Hello Kitty is not pleased.
[Thanks, Chris]
Confused pig face mobile phone has paw print buttons, Winnie the Pooh sticker originally appeared on Engadget on Sun, 18 Apr 2010 02:23:00 EST. Please see our terms for use of feeds.
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Tagi: pig face, paw print, dney, kirf, rear speakers, camera light, maced, phe, jaunt, extreme cases, smattering, clamshell, butts, gadget, hg, kitty, sectors, gadgets, mobile phone, nbsp
Posted by on under storage densities, wder, orders of magnitude, perpendicular recording, bpr, megabits, vengeance, rae, sectors, diameter, nbsp, twins, gb |
Just when we think that platter-based storage is on its way out it keeps on coming back with a vengeance. A few years ago it was
perpendicular recording boosting storage densities by a few orders of magnitude, now it's a pair of new techniques that could push things much further. Your average disk today can manage a couple-hundred GB per square inch while still delivering reliable writes, but if all goes to plan the write methods called bit-patterned recording (BPR) and thermally-assisted recording (TAR) could raise that to 1TB per inch initially and upwards of 10TB per inch down the road. BPR relies on segregating the disk sectors with lithographed "islands" while TAR relies on heating and cooling techniques that preserve the data in nearby sectors. When these Wonder Twins combine, disk sectors can be as small as 15nm in diameter and write speeds can hit 250Mb/sec. Yes, that's megabits, so while you'll be able to store a lot more data than on conventional platters, you won't be able to do so any more quickly than now.
New HDD writing methods could boost platter densities by 5x or more originally appeared on Engadget on Mon, 10 May 2010 13:45:00 EST. Please see our terms for use of feeds.
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Tagi: storage densities, wder, orders of magnitude, perpendicular recording, bpr, megabits, vengeance, rae, sectors, diameter, nbsp, twins, gb
