[EVO 4G Q&A, Help & Troubleshooting] cabello123:
http://revolutionary.io/

http://unrevoked.com/rootwiki/doku.php/public/revolutionary

Just confirmed this with revolutionary here http://webchat.freenode.net/?channels=revolutionary

Response today:

[12:57] <@hyuh> Support channel for revolutionary

[12:57] <cabello123> ok thanks

[12:58] <cabello123> In http://unrevoked.com/rootwiki/doku.php/public/revolutionary Common Problems & Questions can you add one for "Caroline failed writing partition mtd: bad block at 0x00000000" please? The guys on xda are saying that is a hardware fault and no more can be done other than replacing the main pcb board? Do revolutionary agree?

[12:58] <@hyuh> yes

[12:58] <@hyuh> !badblock

[12:58] <@Revolutionary`> badblock is If you get "Not writing bad block at 0xXXXXXXX" errors while running Revolutionary, you have a hardware error on your NAND. We have no workaround for that at the moment, sorry. Try to replace the device with some lame excuse

[12:59] <cabello123> ok thanks very much for the advice cheers - love your work - it is revolutionary! :)

The NAND is memory on the main PCB and nothing to do with the SD card btw for anyone that doesn't know.

Shame that - no new ROM's for me :(

---------- Post added at 01:56 PM ---------- Previous post was at 01:15 PM ----------

[13:19] <cabello123> Mine is @ 0x00000000 - wondering if they've put some sort of block on the NAND addressing - maybe in hardware? Who knows

'they've' ^^^ meaning HTC (so the device would require chipping like a games console) only an idea/possibility

[13:26] <@hyuh> cabello123: no it's not a deliberate thing, we just don't have a way of handling bad blocks at this time.

This last reply from revolutionary may mean that the block writing software that they are using is not capable of mapping out bad blocks? The blocks could be in the NAND from the start and HTC use an intelligent programmer to map around them?

If this is not the case then who ever's NAND chip HTC is using is a pretty poor device for going faulty! That's considering all the posts on the net about this issue.

Anyone know the NAND chip manufacturer and part number used in the hTC desire?

---------- Post added at 02:06 PM ---------- Previous post was at 01:56 PM ----------

This could be the root cause of the bad block problem...

http://en.wikipedia.org/wiki/Flash_memory

NAND memories

"NAND devices also require bad block management by the device driver software, or by a separate controller chip. SD cards, for example, include controller circuitry to perform bad block management and wear leveling. When a logical block is accessed by high-level software, it is mapped to a physical block by the device driver or controller. A number of blocks on the flash chip may be set aside for storing mapping tables to deal with bad blocks, or the system may simply check each block at power-up to create a bad block map in RAM. The overall memory capacity gradually shrinks as more blocks are marked as bad."

It's looking like the devices that work with revolutionary just happen to have all good NAND blocks in the range that revolutionary accesses/reprograms. The ones that don't work have 'mapped out blocks' by the system - perfectly good NAND chips but need to be bad block managed by the filing system etc.

What can revolutionary do to implement bad block management into their exe?