linux-device-driver

I am trying to understand the init process in the linux kernel which is the first process and is statically initialized with the INIT_TASK macro. 161 #define INIT_TASK(tsk) \ 162 { \ 163 .state = 0, \ 164 .stack = &init_thread_info, \ 165 .usage = ATOMIC_INIT(2), \ 166 .flags = PF_KTHREAD, \ 167 .prio = MAX_PRIO-20, \ 168 .static_prio = MAX_PRIO-20, \ 169 .normal_prio = MAX_PRIO-20, \ 170 .policy = SCHED_NORMAL, \ 171 .cpus_allowed = CPU_MASK_ALL, \ 172 .nr_cpus_allowed= NR_CPUS, \ 173 .mm = NULL, \ 174 .active_mm = &init_mm, \ 175 .se = { \ 176 .group_node = LIST_HEAD_INIT(tsk.se.group_node),

I am able to follow a jni tutorial just fine. But when I change the method name, I run into trouble. Is there a naming convention I need to follow? The tutorial used HelloJNI as the module name, and library name. I used "useaaacom". I got great feedback on this and i am making progress. I have a related question; let me know if I should create another post for it. I like to build on this app, which runs at this point. How do I call functions from a device driver? I have the header file, and the driver is loaded into my image. By "how" I mean, do I need to have a copy of the header file in my

I need to control an HCI device directly without the Linux drivers/kernel interfering. For example, when creating an LE connection to a peripheral, the driver is independently sending an "LE Connection Update" command which I would like to avoid. I though of two approaches to resolve this: Configure the bluetooth drivers to somehow disable interference with the HCI device (similar to the -r flag on hciattach), then control the HCI device using a regular AF_BLUEOOTH socket. Disable this particular HCI device, but keep the parent char device and connect to it directly. So far I did not succeed

I am trying to understand the NAPI enabled Network driver and have some doubts regarding the same. If I talk about in layman's term whenever a network packets comes at the interface, it is notified to CPU and appropriate Ethernet driver(interrupt handler) code is executed.Ethernet driver code then copy the packet from Ethernet's Device memory to DMA buffers and finally packets are pushed to upper layer. Is above true for NAPI disabled Ethernet driver? Now for NAPI enabled Ethernet driver initially whenever packets comes at interface ,it is notified to CPU and appropriate Ethernet driver code

I am learning linux network driver recently, and I wonder that if I have many network cards in same type on my board, how does the kernel drive them? Does the kernel need to load the same driver many times? I think it's not possible, insmod won't do that, so how can I make all same kind cards work at same time? regards The state of every card (I/O addresses, IRQs, ...) is stored into a driver-specific structure that is passed (directly or indirectly) to every entry point of the driver which can this way differenciate the cards. That way the very same code can control different cards (which

I'm learning about the registration of a kernel module using register_chrdev_region(dev_t from, unsigned count, const char * name); . I notice that with or without this function, my kernel module worked as expected. The code I used for testing: first = MKDEV(MAJOR_NUM, MINOR_NUM); register_chrdev_region(first, count, DEVICE_NAME);//<---with and without mycdev=cdev_alloc(); mycdev->ops= &fops; mycdev->owner = THIS_MODULE; if (cdev_add(mycdev,first, count) == 0) {printk(KERN_ALERT "driver loaded\n");} I commented out the line register_chrdev_region(first, count, DEVICE_NAME); , and the printk