#1905 NORM Untriag: flash corruption

[Zarro Boogs per Child]

#1905: flash corruption
----------------------+-----------------------------------------------------
 Reporter:  dwmw2     |       Owner:  mlj      
     Type:  defect    |      Status:  new      
 Priority:  normal    |   Milestone:  Untriaged
Component:  hardware  |     Version:           
 Keywords:            |    Verified:  0        
----------------------+-----------------------------------------------------
 A B2 machine was handed to me which failed to boot from NAND, with
 OpenFirmware complaining of 'unknown node type 2006'.

 This is a somewhat bogus diagnostic message from OpenFirmware. It _does_
 understand the node type 0x2006, which is a summary node. It's just that
 these ones have bad CRCs.

 There seems to have been corruption on the write path, between CPU, RAM
 and CAFÉ. An example...

 {{{
 01fdb310  30 17 eb 15 21 00 00 3b  85 19 01 e0 36 00 00 00
 |0...!..;....6...|
 01fdb320  a4 e1 55 df 60 05 00 80  3d 06 00 00 3f 06 00 00
 |..U.`...=...?...|
 01fdb330  a1 a5 0a 46 0e 08 00 00  06 7e be ae 18 18 99 b3
 |...F.....~......|
 01fdb340  70 69 6e 6b 5f 72 6f 75  6e 64 2e 67 69 66 ff ff
 |pink_round.gif..|
 }}}

 This provokes the following report from the kernel:
  JFFS2 notice: (2554) read_direntry: header CRC failed on dirent node at
 0x1fdb318: read 0xaebe7e06, calculated 0x1432b5ee

 The parent inode value of 0x8000560 looks very suspicious. Flipping the
 msb of the byte at 01fdb327 back to a more reasonable 0x00 makes the crc32
 match what's on the flash.

 There are no ECC errors reported -- what's on the flash seems to be what
 reached the CAFÉ in the DMA transfer when this block was being written. So
 this doesn't seem to be an error between CAFÉ and NAND. And the crc32
 seems sane too, so it doesn't seem likely that it's memory corruption or
 program error. I suspect hardware.

 I'll look at other nodes (there are many broken ones) and see if there's a
 pattern to the corruption.

-- 
Ticket URL: <http://dev.laptop.org/ticket/1905>
One Laptop Per Child <http://laptop.org/>