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jffs2: Empty flash at 0xXXXXXXXX ends at 0xXXXXXXXX
jffs2: Empty flash at 0xXXXXXXXX ends at 0xXXXXXXXX
jffs2: Empty flash at 0xXXXXXXXX ends at 0xXXXXXXXX
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jffs2: jffs2_scan_eraseblock(): Magic bitmask 0xXXXX not found at 0xXXXXXXXX: 0xXXXX instead
jffs2: jffs2_scan_eraseblock(): Magic bitmask 0xXXXX not found at 0xXXXXXXXX: 0xXXXX instead
jffs2: jffs2_scan_eraseblock(): Magic bitmask 0xXXXX not found at 0xXXXXXXXX: 0xXXXX instead
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jffs2: Further such events for this erase block will not be printed
以下のページに jffs2 に関する FAQ が掲載されていますが、「JFFS2 generates messages, is there a problem?」のタイトルでご質問の内容が掲載されています。
http://www.linux-mtd.infradead.org/faq/jffs2.html
（抜粋）
JFFS2 generates messages, is there a problem?
JFFS2 adopts the philosophy of keeping the user completely appraised of what is going on.
This can catch out the unwary novice. The following messages can be moved to a higher log level once you are sure that they are benign.
Empty flash at 0xXXXXXXXX ends at 0xXXXXXXXX
This message is generated if a block of data is partially written. It is generally not a sign of any problem.
：
一例として、電源断等、Flash への書き込み途中で終了した場合に発生する旨の記載があります。
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