基于linux 3.10的yaffs2移植

最近想起来还有一块mini2440的开发板很久没有使用了，所以想移植一个基于linux3.10的linux系统，但是在移植yaffs2文件系统的时候出现了一些问题，我将其记录下来给其他同学解决同样的问题提供帮助。

1. 首先通过git下载yaffs2代码。然后进入yaffs2文件夹中执行patch-ker.sh，给linux源代码打上patch。

$ git clone git://www.aleph1.co.uk/yaffs2
$ cd yaffs2/
$ ./patch-ker.sh c m ../linux3.10-mini2440

2. 然后在linux的源代码fs中多了一个yaffs2的文件夹，到此yaffs2文件系统就已经添加到linux3.10中了。在Linux内核源代码根目录运行：make menuconfig，移动上下按键进行配置：

File Systems
	---> Miscellaneous filesystems
		---> [*]YAFFS2 file system support

并按空格选中它，这样我们就在内核中添加了yaffs2文件系统的支持，按“Exit”退出内核配置。

3. 编译linux源代码。

$ make zImage
scripts/kconfig/conf --silentoldconfig Kconfig
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
make[1]: `include/generated/mach-types.h‘ is up to date.
  CALL    scripts/checksyscalls.sh
  CC      scripts/mod/devicetable-offsets.s
  GEN     scripts/mod/devicetable-offsets.h
  HOSTCC  scripts/mod/file2alias.o
  HOSTLD  scripts/mod/modpost
  CHK     include/generated/compile.h
  CC      fs/yaffs2/yaffs_ecc.o
  CC      fs/yaffs2/yaffs_vfs.o
fs/yaffs2/yaffs_vfs.c: In function ‘yaffs_proc_debug_write‘:
fs/yaffs2/yaffs_vfs.c:3304: warning: comparison of distinct pointer types lacks a cast
fs/yaffs2/yaffs_vfs.c: In function ‘init_yaffs_fs‘:
fs/yaffs2/yaffs_vfs.c:3398: error: implicit declaration of function ‘create_proc_entry‘
fs/yaffs2/yaffs_vfs.c:3399: warning: assignment makes pointer from integer without a cast
fs/yaffs2/yaffs_vfs.c:3402: error: dereferencing pointer to incomplete type
fs/yaffs2/yaffs_vfs.c:3403: error: dereferencing pointer to incomplete type
fs/yaffs2/yaffs_vfs.c:3404: error: dereferencing pointer to incomplete type
make[2]: *** [fs/yaffs2/yaffs_vfs.o] Error 1
make[1]: *** [fs/yaffs2] Error 2
make: *** [fs] Error 2

编译fs/yaffs2/yaffs_vfs.c时出现错误，function ‘create_proc_entry‘没有申明。Google之后才知道原来这个接口在linux-3.10被删除了，应该使用proc_create代替。

参考：What‘s coming in 3.10, part 2

4. 修改fs/yaffs2/yaffs_vfs.c

@@ -3384,12 +3384,6 @@ static struct file_system_to_install fs_to_install[] = {
        {NULL, 0}
 };
 
+static const struct file_operations yaffs_fops = {
+        .owner = THIS_MODULE,
+        .read = yaffs_proc_read,
+        .write = yaffs_proc_write,
+};
+
 static int __init init_yaffs_fs(void)
 {
        int error = 0;
@@ -3401,9 +3395,9 @@ static int __init init_yaffs_fs(void)
        mutex_init(&yaffs_context_lock);
 
        /* Install the proc_fs entries */
+       my_proc_entry = proc_create("yaffs",
+                                         S_IRUGO | S_IFREG, YPROC_ROOT, &yaffs_fops);
+#if 0
-       my_proc_entry = create_proc_entry("yaffs",
-                                         S_IRUGO | S_IFREG, YPROC_ROOT);
-
        if (my_proc_entry) {
                my_proc_entry->write_proc = yaffs_proc_write;
                my_proc_entry->read_proc = yaffs_proc_read;
@@ -3411,7 +3405,7 @@ static int __init init_yaffs_fs(void)
        } else {
                return -ENOMEM;
         }
+#endif
-
        /* Now add the file system entries */
 
        fsinst = fs_to_install;

5. 修改之后保存，然后再编译就可以成功了。

$ make zImage
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
make[1]: `include/generated/mach-types.h‘ is up to date.
  CALL    scripts/checksyscalls.sh
  CC      scripts/mod/devicetable-offsets.s
  GEN     scripts/mod/devicetable-offsets.h
  HOSTCC  scripts/mod/file2alias.o
  HOSTLD  scripts/mod/modpost
  CHK     include/generated/compile.h
  CC      fs/yaffs2/yaffs_vfs.o
fs/yaffs2/yaffs_vfs.c: In function ‘yaffs_proc_debug_write‘:
fs/yaffs2/yaffs_vfs.c:3304: warning: comparison of distinct pointer types lacks a cast
fs/yaffs2/yaffs_vfs.c: At top level:
fs/yaffs2/yaffs_vfs.c:3389: warning: initialization from incompatible pointer type
fs/yaffs2/yaffs_vfs.c:3390: warning: initialization from incompatible pointer type
  CC      fs/yaffs2/yaffs_guts.o
  CC      fs/yaffs2/yaffs_checkptrw.o
  CC      fs/yaffs2/yaffs_packedtags1.o
  CC      fs/yaffs2/yaffs_packedtags2.o
  CC      fs/yaffs2/yaffs_nand.o
  CC      fs/yaffs2/yaffs_tagscompat.o
  CC      fs/yaffs2/yaffs_tagsmarshall.o
  CC      fs/yaffs2/yaffs_mtdif.o
  CC      fs/yaffs2/yaffs_nameval.o
  CC      fs/yaffs2/yaffs_attribs.o
  CC      fs/yaffs2/yaffs_allocator.o
  CC      fs/yaffs2/yaffs_yaffs1.o
  CC      fs/yaffs2/yaffs_yaffs2.o
  CC      fs/yaffs2/yaffs_bitmap.o
  CC      fs/yaffs2/yaffs_summary.o
  CC      fs/yaffs2/yaffs_verify.o
  LD      fs/yaffs2/yaffs.o
  LD      fs/yaffs2/built-in.o
  LD      fs/built-in.o
  LINK    vmlinux
  LD      vmlinux.o
  MODPOST vmlinux.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  LD      init/built-in.o
  KSYM    .tmp_kallsyms1.o
  KSYM    .tmp_kallsyms2.o
  LD      vmlinux
  SORTEX  vmlinux
  SYSMAP  System.map
  OBJCOPY arch/arm/boot/Image
  Kernel: arch/arm/boot/Image is ready
  GZIP    arch/arm/boot/compressed/piggy.gzip
  AS      arch/arm/boot/compressed/piggy.gzip.o
  LD      arch/arm/boot/compressed/vmlinux
  OBJCOPY arch/arm/boot/zImage
  Kernel: arch/arm/boot/zImage is ready