This is a historic thing. USE_GENERIC_RW uses the Linux page cache for read/write. This means that the Linux generic_read and generic_write functions are used which and YAFFS supplies the read_page write_page calls. Not defining USE_GENERIC_RW directly implements read/write without using the page cache. The direct read/write stuff was iimplemented first, and I followed it by generic read/write when memory mapping was implemented. During the transition both options worked. Things have now moved on and not defining USE_GENERIC_RW is broken, with no real motivation to fix it. Ie. You should always define USE_GENERIC_RW. This comes up every couple of months on the list. I guess I should pull it out. -- Charles -----Original Message----- From: yaffs-admin@stoneboat.aleph1.co.uk [mailto:yaffs-admin@stoneboat.aleph1.co.uk] On Behalf Of Ulla Sent: Thursday, 14 October 2004 11:40 a.m. To: yaffs@stoneboat.aleph1.co.uk Subject: [Yaffs] CONFIG_YAFFS_USE_GENERIC_RW Hi, I am using yaffs (CVS) (linux 2.6.8.1, mtd-snapshot: 20041005), and I am able to mount the device properly, to write to the flash and erase from the flash. But with CONFIG_YAFFS_USE_GENERIC_RW disabled copying back (or cat) doesn't work, it is running in an endless loop. For example, catting a simple text file will endlessly repeat the contents of that file. Copying a file will not end & create a huge file at the destination. By enabling CONFIG_YAFFS_USE_GENERIC_RW everything is ok. Can someone explain what are the benefits of disabling CONFIG_YAFFS_USE_GENERIC_RW (like it is in the default Makefile) and what are the exact differences between generic_rw and yaffs_rw? Thanks a lot Ulla -- Bluewater Systems Ltd - ARM Technology Solution Centre         Ulrike Eisenmann                        Bluewater Systems Ltd Phone: +64 3 3779127 (Aus +1 800 148 751)       Level 17, 119 Armagh St Fax:   +64 3 3779135                            PO Box 13889 Email: ulla@bluewatersys.com                  Christchurch Web:   http://www.bluewatersys.com              New Zealand _______________________________________________ yaffs mailing list yaffs@stoneboat.aleph1.co.uk http://stoneboat.aleph1.co.uk/cgi-bin/mailman/listinfo/yaffs