?? : Dummy ???? ???? ?? ? ??

1
?? ???? ????

• ???? ???

2
??

• ?? ??
• ?? ??
• ?? ?? ?? ??
• ??? ???? ????
• ?? Dummy ???? ???? ?? ? ??

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kernel configuration

• ?? kernel ??? ?? ???
• MTD file system? mount?? ?? ???

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system type
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Serial drivers

• Device drivers -gt Character devices -gt Serial
  drivers

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Boot options
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MTD

• Device drivers -gt Memory Technology Devices (MTD)
  -gt

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MTD

• Device drivers -gt Memory Technology Devices (MTD)
  -gt
• Ram/Rom/Flash chip drivers

9
MTD

• Device drivers -gt Memory Technology Devices (MTD)
  -gt
• Mapping drivers for chip access

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File systems

• File systems -gt Miscellaneous filesystems -gt

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?? ??

• ??? ?? ?? ???? loading ? ? ?? ?? ????
• ??? ?? ??? ??? ??? ??? ? ?? ?? ??? ???? ???? ??
  ??
• ???? ????, ?? ???, ???? ???? ?? ??? ???
• ???? ?? ?? ??? ???? ??, ?? ???? ?? ?? ??? ???? ?
• ltlinux/module.hgt? ???? ??
• ?? ??? ?? ???? ??? ???? ?
• ?? ?? ?????? ???
• main() ??? ??
• ??? ?? ? ?? ? ? ???? ??? ??
• Loading ? - int init_module(void) ?? ??
• Unloading ? - void cleanup_module() ?? ??

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?? ?? ?? ??

• Hello World ????
• ??? ??? ?
• Hello world ??
• ??? ??? ?
• Goodbye world ??

• / hello.c /
• include ltlinux/module.hgt / ?? ??? ?? /
• include ltlinux/kernel.hgt / printk() ?? ?? /
• int hello_init(void) // ??? ??? ? ??
• printk (Hello world\n)
• return 0
• void hello_exit(void) // ?? ? ? ??
• printk (Goodbye world)
• module_init(hello_init)
• module_exit(hello_exit)
• MODULE_LICENSE(GPL)

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?? ?? ?? ???

• arm-linux-gcc ????? ??
• ???? ?? Makefile ??

• Makefile
• obj-m hello.o
• KDIR (?? ??? ??? ?? ??)
• PWD (shell pwd)
• all
• (MAKE) -C (KDIR) SUBDIRS(PWD) modules
• clean
• rm -rf .ko
• rm -rf .mod.
• rm -rf ..cmd
• rm -rf .o

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?? ?? ?? ?? ??

• ??? ??? ??
• rx hello.ko
• ??? ??(x??)? ?? ???? ???? ko ?? ??
• insmod hello.ko
• ??? ??? ?? ?? ??
• lsmod
• ?? ??
• rmmod hello
• ?? ??? ?? ?? ?? ???? ????? ???? ? ??

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??? ???? ????

• ?? ?? ??? ??? ?? ??? ????? ???? ?????? ?? ?????
  ??? ? ??? ??? ????
• ???? ??? ??? ???? ????? ??? ???? ??? ????? ???
• ????? ?? ??? ??? ???? ??? ????? ??
• ???? ???? ????? ??? ???? ?
• ?? ??? ?? ??? ??

16
??? ???? ????? ??

• ?? ???? ????
• ??? ???? ?? ??
• ????? ???? ??? ??? ??
• ?) ???, ??? ?? ?
• ?? ???? ????
• ?? ??? ??? ???
• ?????? ??? ?? ???? ??
• ????? ???? ??? ??? ??? ??
• ?) ?? ???, CD?, ??? ??? ?
• ???? ???? ????
• ???? ????? ??
• ???????? ??? ?? ?? ????? ? ?? socket(), bind() ??
  ??? ? ??

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??? ???? ????? ??(2)
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???? ?? ??

• ????? ??? ??? ???
• ls l /dev ??? ???? ?? ??

???? ??
???
???
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???? ?? ??(2)

• ? ??(Major Number)
• ???? ???? ????? ??/????? ??
• ?? Device? ??? ??, 1Byte (0255??? ?)
• ? ??(Minor Number)
• ???? ???? ??? ??? ???? ?? ??
• ? Device? ???? ??? ???, 2Byte (???)
• ??? ???? ????? ?? ?? ???? ?? ??

???
???
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?? ???? ???? ?? ??
include ltlinux/kernel.hgt include ltlinux/module.hgt include ltlinux/init.hgt
int device_open( ) int device_release( ) ssize_t device_write( ) ssize_t device_read( )
static struct file_operations device_fops ssize_t (read) () ssize_t (write) () int (open) () int (release) ()
int init_module(void) void cleanup_module(void)
module_init(hello_init) module_exit(hello_exit)
?? ??
?? ?? ?? ??
?? ?? ???
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???? ???? ?? ??

• ???? ???? ??
• ????? ??? ????, ?? ??? ???? ?? ??? ?? ??? ??
• insmod? ???? ??? ??? ??? ? init???? ??? ??
• ?? ???? ?? ??
• ??? ???? ?? chrdevs ??? ??? ?? ???? ??
• major number ???, 0? ?? ???? ?? ?? ??
• name ???? ???? /proc/devices? ???
• fops ????? ??? ?? ?? ??? ???
• ??? ???? ??? ????? ???

int register_chrdev( unsigned int major, const
name, struct file_operations fops)
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???? ???? ?? ??(2)

• ???? ???? ??
• rmmod ???? ????? ??? ? cleanup ???? ??
• ?? ???? ?? ??

int unregister_chrdev( unsigned int major, const
name)
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???? ???? ?? ??(3)

• ?? ?? ??? ??
• ???? ????? ???? ??? ??? ?????? ???? ??
• ? ????? ?? ??? ????, ??? ?? ??? ???? I/O ???
  ????? ????? ??
• ???? ????? ????? ?? ???? ???? ????? ???? ????
  ????? ??? ?? ??

struct file_operations dummy_fops .owner
THIS_MODULE, .open dummy_open,     .read
dummy_read,         .write dummy_write,   
    .ioctl dummy_ioctl     .release
dummy_release,  
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???? ???? ?? ??(4)

• ?? ??? ??
• read
• ?????? ???? ???? ??? ??
• write
• ????? ???? ?? ??? ??
• ioctl
• ????? ???? ??? ??? ?? ??
• mmap
• ???? ???? ???? ???? ??
• open
• ????? ? ? ??
• release
• ????? ?? ? ??

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?? Dummy ???? ???? ??

• ?? ?? ? ??? ??

include ltlinux/module.hgt include
ltlinux/kernel.hgt include ltlinux/fs.hgt include
ltlinux/errno.hgt include ltlinux/types.hgt include
ltlinux/fcntl.hgt define DUMMY_NAME
dummy define DUMMY_MAJOR_NUMBER 240
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?? Dummy ???? ???? ??(2)

• ???? ??

static int dummy_init(void)         int
ret         printk(dummy init\n)     
ret register_chrdev(DUMMY_MAJOR_NUMBER,     
        DUMMY_NAME, dummy_fops)         if
(res lt 0)                 return
ret         return 0 module_init(dummy_init)
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?? Dummy ???? ???? ??(3)

• ???? ??

static void dummy_exit(void)
        printk(dummy exit\n)         unregist
er_chrdev( DUMMY_MAJOR_NUMBER,     
        DUMMY_NAME) module_exit(dummy_exit)
MODULE_LICENSE(GPL)
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?? Dummy ???? ???? ??(4)

• ?? ?? ??? ??

struct file_operations dummy_fops .owner
THIS_MODULE, .open dummy_open,   .read
dummy_read,         .write dummy_write,   
   .ioctl dummy_ioctl,     .release
dummy_release,  
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?? Dummy ???? ???? ??(5)

• open release

int dummy_open(struct inode inode, struct file
filep)         int num MINOR(inode-gti_rdev)
        printk(dummy dev open -gt minor d\n,
num)         return 0 int
dummy_release(struct inode inode, struct file
filep)         printk(dummy dev
close\n)         return 0
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?? Dummy ???? ???? ??(6)

• read write

size_t dummy_read(struct file filep, char buf,
size_t count, loff_t f_pos)         printk(du
mmy dev read -gt buf 0x08x, count 0x08x\n, buf,
count)         return 0x33 size_t
dummy_write(struct file filep, const char buf,
size_t count,         loff_t f_pos)
        printk(dummy dev write -gt buf 0x08x,
count 0x08x\n, buf, count)         return
0x43
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?? Dummy ???? ???? ??(7)

• ioctl

int dummy_ioctl(struct inode inode, struct file
filep,         unsigned int cmd, unsigned long
arg)         printk(dummy dev ioctl -gt cmd
0x08x, arg 0x08x\n, cmd, arg)         return
0x53
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?? Dummy ????? ???? ?? ?????? ??

• app.c

include ltstdio.hgt include ltsys/types.hgt include
ltsys/stat.hgt include ltsys/ioctl.hgt include
ltfcntl.hgt include ltunistd.hgt define DEV_NAME
/dev/dummy_device int main()         int
dev         char buf128         int
ret         printf(1gt device
open\n)         dev open(DEV_NAME,           
      O_RDWRO_NDELAY)         printf(dev
d\n, dev)         if (dev gt 0)         
                printf(2gt read
function\n)                 ret read(dev,
0x30, 0x31)                 printf(ret
0xx08x\n, ret)                 printf(3gt
write function\n)                 ret
write(dev, 0x40, 0x41)                 printf(re
t 0xx08x\n, ret)                 printf(4gt
ioctl function\n)                 ret
ioctl(dev, 0x51, 0x52)                 printf(re
t 0xx08x\n,                 printf(5gt
device close\n)                 ret
close(dev)                 printf(ret
0xx08x\n, ret)                  return 0
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?? ???? ???? ?? ? ??

• ???? ???? ???
• ?? ?? ??? ??
• ???? ???? ??
• insmod dummy.ko
• ?? ??
• ????? ???? ???? ??(??)? ???? ?
• ??(??)? ??? ??? ??
• mknod /dev/dummy_device c 240 0
• ???? ???? ??
• rmmod dummy
• ????? ?? ??
• lsmod