ldd3 源碼編譯之 scullc 字符設備驅動

轉自：http://blog.chinaunix.net/uid-25381054-id-3261527.html

使用內核版本-linux-3.2

錯誤1：

make -C /lib/modules/3.2.0/build
M=/home/wrk/works/drivers/ldd3/examples/scullc
LDDINC=/home/wrk/works/drivers/ldd3/examples/scullc
modules
make[1]: Entering directory `/home/wrk/works/drivers/linux-kernel/linux-3.2'
scripts/Makefile.build:49: *** CFLAGS
was changed in "/home/wrk/works/drivers/ldd3/examples/scullc/Makefile". Fix it to use
ccflags-y. Stop.
make[1]: *** [_module_/home/wrk/works/drivers/ldd3/examples/scullc] Error 2
make[1]: Leaving directory `/home/wrk/works/drivers/linux-kernel/linux-3.2'
make: *** [modules] Error 2

這個錯誤還比較好解決，像提示的那樣在Makefile中用ccflags-y替換CFLAGS 

錯誤2：

/home/wrk/works/drivers/ldd3/examples/scullc/main.c:52:1: error: unknown type name ‘kmem_cache_t’

這是因爲kmem_cache_t結構被換成了kmem_cache。而kmem_cache定義在<linux/slab_def.h>和<linux/slub_def.h>。但是你並不需要包含這兩個文件中的一個。因爲<linux/slab.h>會根據CONFIG_SLUB等來判斷具體包含<linux/slab_def.h>，還是<linux/slub_def.h>。故例程中需要將

kmem_cache_t *scullc_cache;
改爲：
struct kmem_cache *scullc_cache;

錯誤3：

/home/wrk/works/drivers/ldd3/examples/scullc/main.c: In function ‘scullc_defer_op’:
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:437:54: error: macro "INIT_WORK" passed 3 arguments, but takes just 2
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:437:2: error: ‘INIT_WORK’ undeclared (first use in this function)

這裏需要將

INIT_WORK(&stuff->work, scull_do_deferred_op, stuff);

改爲：

INIT_WORK(&stuff->work, scull_do_deferred_op);

並且將scullc_do_deferred_op函數改爲

static void scullc_do_deferred_op(struct work_struct *p)
{
        struct async_work *stuff = container_of(p, struct
async_work, work);
        aio_complete(stuff->iocb, stuff->result, 0);
        kfree(stuff);
}

錯誤4： 

/home/wrk/works/drivers/ldd3/examples/scullc/main.c:467:2: error: unknown field ‘ioctl’ specified in initializer

這裏因爲內核接口變化需要將.ioctl改爲 .unlocked_ioctl

錯誤5：

/home/wrk/works/drivers/ldd3/examples/scullc/main.c:558:4: error: too many arguments to function ‘kmem_cache_create’

函數kmem_cache_create的原型已經改變：
struct kmem_cache *kmem_cache_create(const char *, size_t, size_t, unsigned long, void (*)(void *));故調用它的時候應該將參數做出相應的改變。需要將最後一個NULL去掉。

下面來解決warning：

/home/wrk/works/drivers/ldd3/examples/scullc/main.c: In function ‘scullc_defer_op’:
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:437:2: warning: assignment from incompatible pointer type [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:438:2: warning: passing argument 1 of ‘schedule_delayed_work’ from incompatible pointer type [enabled by default]
include/linux/workqueue.h:363:12: note: expected ‘struct delayed_work *’ but argument is of type ‘struct work_struct *’
/home/wrk/works/drivers/ldd3/examples/scullc/main.c: At top level:
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:467:2: warning: initialization from incompatible pointer type [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:467:2: warning: (near initialization for ‘scullc_fops.unlocked_ioctl’) [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:470:2: warning: initialization from incompatible pointer type [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:470:2: warning: (near initialization for ‘scullc_fops.aio_read’) [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:471:2: warning: initialization from incompatible pointer type [enabled by default]
/home/wrk/works/drivers/ldd3/examples/scullc/main.c:471:2: warning: (near initialization for ‘scullc_fops.aio_write’) [enabled by default]

1.把

struct async_work {
struct kiocb *iocb;
int result;
struct work_struct work;
};

改爲：

struct async_work {
struct kiocb *iocb;
int result;
struct delayed_work delayed_work;
}

然後把：

INIT_WORK(&stuff->work, scull_do_deferred_op, stuff);
schedule_delayed_work(&stuff->work, HZ/100);

改爲：

INIT_DELAYED_WORK(&(stuff->delayed_work), scullc_do_deferred_op);
schedule_delayed_work(&(stuff->delayed_work), HZ/100);

再編譯即可通過。