Thread: Error with DD for /dev/mtdblock4??
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fanoush is offline fanoush
2008-02-22 , 09:58
Posts: 2,152 | Thanked: 1,490 times | Joined on Jan 2006 @ Czech Republic
#4
Such errors look exactly like having bad blocks in the flash and are somewhat 'normal'. Flash memory can have few bad blocks from factory (similar to bad pixels on LCD monitors), when device boots it scans for them and should not use them, here is my output with N810

Code:
[    0.570312] OMAP2 OneNAND driver initializing
[    0.570312] omap2-onenand omap2-onenand: initializing on CS0, phys base 0x04000000, virtual base c8880000
[    0.570312] OneNAND Manufacturer: Samsung (0xec)
[    0.570312] Muxed OneNAND 256MB 1.8V 16-bit (0x40)
[    0.570312] OneNAND version 0x0022
[    0.593750] Scanning device for bad blocks
[    0.679687] onenand_bbt_wait: controller error = 0x2440
[    0.679687] Bad eraseblock 1399 at 0x0aee0000
[    0.718750] Creating 5 MTD partitions on "omap2-onenand":
[    0.718750] 0x00000000-0x00020000 : "bootloader"
[    0.718750] 0x00020000-0x00080000 : "config"
[    0.718750] 0x00080000-0x00280000 : "kernel"
[    0.726562] 0x00280000-0x00480000 : "initfs"
[    0.726562] 0x00480000-0x10000000 : "rootfs"
I have one bad block in rootfs too and reading whole /dev/mtdblock4 via dd fails for me too (with same error). Jffs2 filesystem should detect it and skip. At least I hope so :-)
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