Hi All, I have a pci driver like: define VENDOR_ID 0x1415 #define DEVICE_ID1 0xc140 #include<linux/module.h> #include<linux/version.h> #include<linux/kernel.h> #include<linux/pci.h> #include<linux/ioport.h> #include<asm/unistd.h> #include<linux/slab.h> #include<linux/fs.h> #include<asm/uaccess.h> #include<asm/io.h> #include<linux/kdev_t.h> #include<asm/fcntl.h> #include<linux/sched.h> #include<linux/wait.h> #include<linux/errno.h> #include<asm/irq.h> #include<asm/ioctl.h> #include<linux/string.h> #include<linux/interrupt.h> init_module (void) { short int curr_device; dev = pci_find_device (VENDOR_ID, DEVICE_ID1, NULL); j = pci_enable_device (dev); curr_device = 0; printk("Init : Reading and writing Config space.........\n"); pci_read_config_word (dev, 0x02, (u16 *)&curr_device); printk("Init : Current Device id = %x\n", (curr_device & 0x00FFFF)); curr_device = 0xc145; pci_write_config_word (dev, 0x02, curr_device); pci_read_config_word (dev, 0x02, (u16 *)&curr_device); printk("Init : After writing to Config space, Current Device id = %x\n", (curr_device & 0x00FFFF)); return 0; } void cleanup_module (void) { printk ("Closing pci \n"); } When I insmod this driver after build, it shows: Jul 20 15:11:03 localhost kernel: Init : Reading and writing Config space......... Jul 20 15:11:03 localhost kernel: Init : Current Device id = c140 Jul 20 15:11:03 localhost kernel: Init : After writing to Config space, Current Device id = c140 Any clues as to why is not writing 0xc145 to the pci config space? curr_device = 0xc145; pci_write_config_word (dev, 0x02, curr_device); Thanks & Regards, D.Giriprasad