This example will create a proc entry which enables reading access. I think you can enable other kinds of access by changing the mode argument passed to the function. I haven’t passed a parent directory because there is no need to. The structure file_operations is where you setup your reading and writing callbacks. struct proc_dir_entry … Read more
M is not an option for make. Note it lacks the hyphen. M is a variable assigned to the execution of make. If make executes a Makefile script, this script can read the variable M and use its contents. In the example you provide, make will read Makefile in ~/kernel-2.6 and assign your present working … Read more
They determine the initialization order of built-in modules. Drivers will use device_initcall (or module_init; see below) most of the time. Early initialization (early_initcall) is normally used by architecture-specific code to initialize hardware subsystems (power management, DMAs, etc.) before any real driver gets initialized. Technical stuff for understanding below Look at init/main.c. After a few architecture-specific … Read more
My list: What an operating system’s concerns are: Abstraction and extension of the physical machine and resource management. How the build process works ie, how architecture specific/machine code stuff is implanted How system calls work and how modules can link up Memory management / Virtual Memory / Paging and all the rest How processes are … Read more
Depends on your current skills. If you’re really new to Linux, perhaps you should start with user space system programming with Advanced Linux Programming. You’ll get good knowledge of Unix system calls and other concepts such as signals, processes/threads and so on with this free resource. This is a must (understanding the user space API) … Read more
I’m actually working on exactly the same thing right now and I’m going the ioctl() route. The general idea is for user space to allocate the buffer which will be used for the DMA transfer and an ioctl() will be used to pass the size and address of this buffer to the device driver. The … Read more
I see the relationship between BSPs and devices drivers as “has-a”. Board support packages include device drivers. The differences between BSPs & kernels isn’t easy to distinguish. A kernel translates instructions to the hardware. Kernels are often written to particular families of hardware, so they’re not as portable or generic as they seem. It amounts … Read more
Often when working close to the hardware or when trying to control the size/format of a data structure you need to have precise control of the size of your integers. As for u8 vs uint8_t, this is simply because Linux predated <stdint.h> being available in C, which is technically a C99-ism, but in my experience … Read more
Certainly in ethtool you can just print the address: -P –show-permaddr Queries the specified network device for permanent hardware address. e.g. ethtool -P eth0 produces Permanent address: 94:de:80:6a:21:25
The reason that documentation is scarce is that it’s an area that’s quite architecture-dependent. The code is really the best documentation – for example, the THREAD_SIZE macro defines the (architecture-dependent) per-thread kernel stack size. The stacks are allocated in alloc_thread_stack_node(). The stack pointer in the struct task_struct is updated in dup_task_struct(), which is called as … Read more