NAND flashÎļþϵͳJFFS2ºÍYAFFS±È½Ï
NAND flashÎļþϵͳJFFS2ºÍYAFFS±È½Ï
ARM9 2009-12-07 21:29:50 ÔĶÁ98 ÆÀÂÛ0 ×ֺţº´óÖÐС
JFFSÊÇÓÉÈðµäµÄAxis Communications Ab¹«Ë¾¿ª·¢µÄ(1999,ÒÔGNU·¢²¼),Õë¶ÔflashÉ豸µÄÌØÐÔΪǶÈëʽÉ豸¿ª·¢µÄ
JFFS1ºÍJFFS2µÄÉè¼ÆÖж¼¿¼Âǵ½ÁËFLASHµÄÌØÐÔÌØ±ðÊÇÂú×ãÁËÉÏÊö3¸öÌõ¼þ,°üÀ¨ÁËÀ¬»ø»ØÊÕ,»µ¿é¹ÜÀíµÈ¹¦ÄÜ. ÕâÁ½ÖÖÎļþϵͳÊôÓÚLFS(Log-structured File System).ÕâÖÖÎļþϵͳµÄÌØµãÊÇÒ»µ©Êý¾Ý³ö´í,ÈÝÒ×»Ö¸´,µ«ÊÇϵͳÔËÐÐÊÇÐèÒªÕ¼ÓÃÒ»¶¨µÄÄÚ´æ¿Õ¼ä,ÕâЩ¿Õ¼ä¾ÍÊÇÓÃÀ´´æ´¢”log”µÄ.
JFFSµÄȱµã¾ÍÊǼÓÔØÊ±¼äÌ«³¤,ÒòΪÿ´Î¼ÓÔØ¶¼ÐèÒª½«FLASHÉϵÄËùÓнڵã(JFFSµÄ´æ´¢µ¥Î»)µ½ÄÚ´æ,ÕâÑùÒ²Õ¼ÓÃÁ˿ɹ۵ÄÄÚ´æ¿Õ¼ä.³ý´ËÖ®Íâ,”circle log”Éè¼ÆÊ¹µÃÔÚ¶ÔÎļþÊý¾Ý½øÐÐËùÓеÄÊý¾Ý¶¼»á±»ÖØÐ´,ÕâÑùÔì³É²»±ØÒªµÄʱ¼ä,ͬʱҲ»á¼õÉÙFLASHµÄÊÙÃü.
JFFS2¶ÔJFFS1×÷ÁËЩ¸Ä½ø,±ÈÈçËùÐèµÄÄÚ´æ±äÉÙÁË,À¬»ø»ØÊÕ»úÖÆÒ²ÓÅ»¯ÁË.
Õë¶ÔJFFS1,JFFS2µÄȱµã,JFFS3³öÏÖÁË.
YAFFS1 & YAFFS2
“Yet Another Flash File System”×÷ÕßÊÇÐÂÎ÷À¼µÄCharles ManningΪһ¼ÒÃû½ÐAlpha one µÄ¹«Ë¾(http://www.aleph1.co.uk/)Éè¼ÆµÄ,ÊǵÚÒ»¸öΪNAND FlashÉè¼ÆµÄÎļþϵͳ.¹²Á½¸ö°æ±¾YAFFS1 ºÍYAFFS2.
YAFFS1Ö§³Ö512Bytes/PageµÄNAND Flash;ºóÕßYAFFS2Ö§³Ö2kBytes/PageµÄNAND Flash. YAFFSÎļþϵͳҲÊôÓÚLFS.
¸úÆäËûÎļþϵͳ±È½Ï,Ëü¾ßÓиüºÃµÄ¿ÉÒÆÖ²ÐÔ,ÉõÖÁ¿ÉÒÔʹÓÃÔÚûÓвÙ×÷ϵͳµÄÉ豸ÉÏ(called “YAFFS/Direct”). YAFFS²ÉÓÃÄ£¿é»¯Éè¼Æ,ËäÈ»×î³õÊÇÓÃÔÚlinuxϵͳÉϵÄ,µ«ÊÇÒ²ÒÑ¾ÒÆÖ²µ½ÆäËûϵͳ±ÈÈçwince.
»¹ÓиöÍ»³öµÄÓŵãÊÇËüÔÚmountµÄʱºòÐèÒªºÜÉÙµÄÄÚ´æ.(Èç¹ûÊÇСҳ¨D512byte/page,ÿ1MByte NAND´óÔ¼ÐèÒª4KBytesÄÚ´æ;´óÒ³ÐèÒª´ó¸Å1KBytes RAM/1MByte NAND)
JFFSÓëYAFFS±È½Ï,Á½Õ߸÷Óг¤´¦. Ò»°ãÀ´Ëµ,¶ÔÓÚСÓÚ64MBytesµÄNAND Flash,¿ÉÒÔÑ¡ÓÃJFFS;Èç¹û³¬¹ý64MBytes,ÓÃYAFFS±È½ÏºÏÊÊ.
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