We have integrated the commercial licensed Yaffs sources into our project and hit a portability issue with GCC.   It turns out that the format of data on flash changes as a result of enums being interpreted as either int (4 bytes) or char (1 byte), depending on the GCC version.

We learned that newer versions of GCC use short enums by default, whereas older versions use int (4 bytes).  Since we're planning to update our GCC compiler in the near future, this will become a serious problem for those devices that need to be field-upgraded.  We could obviously use the -fno-short-enums for the Yaffs source code to maintain compatibility, but it would probably help us and many others if some changes are made to the source code.

One of the problematic sections is in yaffs_guts.h:

struct yaffs_obj_hdr {
    enum yaffs_obj_type type;

    /* Apply to everything  */
    int parent_obj_id;

Unsurprisingly, the device crashes when running Yaffs built with an older version of GCC, if the device previously ran binaries produced with a newer version of GCC:

U1_2 (Stopped - Step End)    

   yaffs_find_by_name() - yaffs_guts.c:4394    

   yaffs_create_obj() - yaffs_guts.c:2186    

   yaffs_create_dir() - yaffs_guts.c:2259    

   yaffs_mkdir_reldir() - yaffsfs.c:2686    

   yaffs_mkdir() - yaffsfs.c:2709