linux-device-driver

I want to learn about how nl80211 and cfg80211 works in detail. Function flow, how nl80211 interact with network tools like wpa_supplicant , iw . Plz suggest me some useful links or books to refer. To be able to control wireless drivers from userspace, some IPC communication processes between kernel and userspace are used. At first ioctl with vendor dependent APIs was used. In 1996, Jean Tourrilhes creates wireless extensions (WE or WEXT). The Wireless Extension (WE) is a generic API allowing a driver to expose to the user space configuration and statistics specific to common Wireless LANs. In

I want to learn lLinux Kernel programming. What would be the starting points for that? What could be some of the simpler problems to target? Try to get hold of Robert Love's book on Linux Kernel Programming. Its very concise and easy to follow. After that or along with that, you may want to take a look at "Understanding the Linux kernel".But I wouldn't recommend it during the early stages. Also, look at the Linux kernel programming guide . Since a lot can be learnt from programing kernel modules, that guide will help you. And yes, for a lot of information, consult the 'documentation' sub

The start address 0x4806E000 (UART4 base address) is already present in /proc/iomem with the name omap4-uart. How to disable the memory regions already allocated ?. Edit : Even though request_mem_region is successful the console during booting shows this messages. [ 0.758514] Serial: 8250/16550 driver, 3 ports, IRQ sharing enabled [ 0.760040] omap_uart.0: ttyO0 at MMIO 0x4806a000 (irq = 104) is a OMAP UART0 [ 0.760498] omap_uart.1: ttyO1 at MMIO 0x4806c000 (irq = 105) is a OMAP UART1 [ 0.760955] omap_uart.2: ttyO2 at MMIO 0x48020000 (irq = 106) is a OMAP UART2 [ 1.778808] console [ttyO2]

Summary (What we've done, what we've tried): Basically, the aim is to establish an adb protocol via usb between two linux computers by using adb source codes. Envinronment is Ubuntu 16.0.4. There's android-tools-adbd (adb daemon) package ready for use in the pool with its source available. There is also a source on this link (adbd) compilable with gcc option -stc=c++14 which is supported in 16.0.4 by default (or gcc 5.2 ). We are able to build the package from source or use already-built one successfully by using adb connect (TCP/IP dependent). There's no problem on adb connection via TCP/IP

Recently I start to develop the linux device driver, I face a problem, when I want to debug with kernel code, and add some printk debug message in the kernel file. for example, recently I add some printk() and dump_stack() in the __debug_locks_off() which resides in include/linux/debug_locks.h . Then I do the following steps, which is very time consuming. make clean make bzImage make modules make modules_install mkinitrfmfs -o /boot/initrd.img 3.12.6[my kernel version] cp arch/x86/boot/bzImage /boot update-grub Then reboot and choose my new kernel version. I don't know if there are some

1) Is it possible to access a physical address which is not defined in /proc/iomem? 2) If the physical address range of a device does not appear in /proc/iomem, does it mean that the device has not been utilized/initialized yet? 1) Is it possible to access a physical address which is not defined in /proc/iomem? Yes. Assuming an ARM processor which memory maps all directly-connected periperals, the driver could perform an ioremap() operation to map the physical memory to virtual memory for access. But a properly written driver would first call request_mem_region() to ensure that it can use (and