The magic bitmask question - again

Fredrik Jönsson B (AL/EAB) fredrik.b.jonsson at
Mon Oct 31 07:31:54 EST 2005

This may be a stupid question, but I still need to ask.

We have a system with a 128Mb NOR-flash of which 3Mb is used as a keep-off area for the kernel and the rest for a JFFS2 root file system. The system boots and mounts properly and everything seems fine, but during mounting a number of messages such as the one below are shown for each of the first four erase-blocks of the mtd partition.

jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000000: 0x4800 instead

Is this the expected behaviour? I've been fiddling with the padding option to mkfs.jffs2 in order to make the message go away without success. I've noted in the JFFS paper that four free flash sectors is "required" for garbage collection to work properly. Is it some sort of spare four sectors that mkfs.jffs2 creates for this purpose or what?

I've seen this question a number of times on the web, but have not seen it properly answered anywhere. 

Grateful for any help on the matter,

	/Fredrik Jönsson

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