The document provides an introduction to Linux and device drivers. It discusses Linux directory structure, kernel components, kernel modules, character drivers, and registering drivers. Key topics include dynamically loading modules, major and minor numbers, private data, and communicating with hardware via I/O ports and memory mapping.

1. INTRODUCTION TO LINUX WORLD PART 1 Mukul Bhardwaj

17. Open source community

26. LINUX CONFIGURATION

33. Introduction to Device Driver framework

35. Device Driver Interface System Call interface User Program Open Read close write Virtual File System Switch DevX_Open DevX_Read DevX_write DevX_close Hardware

67. Character Driver

98. ATAG Parameter List Command line to pass to kernel 2(length_of_cmdline + 3) / 4) 0x54410009 ATAG_CMDLINE Initial values for vesafb-type framebuffers 8 0x54410008 ATAG_VIDEOLFB 32 bit board revision number 3 0x54410007 ATAG_REVISION 64 bit board serial number 4 0x54410006 ATAG_SERIAL Describes where the compressed ramdisk image is placed in memory 4 0x54420005 ATAG_INITRD2 Describes how the ramdisk will be used in kernel 5 0x54410004 ATAG_RAMDISK Describes a VGA text display 5 0x54410003 ATAG_VIDEOTEXT Describes a physical area of memory 4 0x54410002 ATAG_MEM First tag used to start list 5 (2 if empty) 0x54410001 ATAG_CORE Empty tag used to end list 2 0x00000000 ATAG_NONE Description Size Value Tag name

114. Kernel Memory Layout on ARM Linux-1

115. Kernel Memory Layout on ARM Linux-2 FFFFFFFF FFFF7FFF FFFF0FFF FFFE FFFF FFBF FFFF FEFF FFFF VMALLOC_END-1 VMALLOC_START high_memory-1 PAGE_OFFSET-1 TASK_SIZE-1 0000 0FFF 0000 0000 Free for platform use, recommended. vmalloc() / ioremap() space. Memory returned by vmalloc/ioremap will be dynamically placed in this region. VMALLOC_START may be based upon the value of the high_memory variable. CPU vector page / null pointer trap CPUs which do not support vector remapping place their vector page here. NULL pointer dereferences by both the kernel and user space are also caught via this mapping. User space mappings Per-thread mappings are placed here via the mmap() system call. Kernel module space Kernel modules inserted via insmod are placed here using dynamic mappings. Kernel direct-mapped RAM region. This maps the platforms RAM, and typically maps all platform RAM in a 1:1 relationship. 0xC000 0000 Reserved for future expansion of DMA mapping region. DMA memory mapping region. Memory returned by the dma_alloc_xxx functions will be dynamically mapped here CPU vector page. The CPU vectors are mapped here if the CPU supports vector relocation (control register V bit.) Reserved. Platforms must not use this address range. copy_user_page / clear_user_page use.

146. Kernel

153. Process States Ready Suspended Running Stopped Zombie Creation Scheduling Termination Signal Signal Signal

169. Virtual vs. Physical Addresses DRAM Size 0 0xFFFFFFFF 0xC0000000 0x10000000 Kernel Application Code Data Heap Thread 1 Stk Thread 2 Stk 2MBs 2MBs Invalid page (256 MB) (3 GB) (4 GB) Main Stk 2MBs 0x80000000 (2 GB) FFF00000h 3.75GB - DRAM Size 224 MB 15 MB 1 MB 1 MB 1 MB 1 MB 6 MB 7 MB 1 MB FF800000h FF300000h FF200000h FF100000h FEF00000h FE000000h F0000000h FFFFFFFFh 0h Boot FLASH Optional Flash Reserved Optional I/O MPIC Registers Reserved On-Board Peripherals PCI/ISA I/O Space Optional Flash PCI Memory Space Local DRAM System Memory PPC

170. Virtual - Physical

176. Page table

179. ARM-Memory Managment Access control hardware ARM Cache and write buffer Cache line fetch hardware TLB Translation table walk hardware Main memory Abort VA PA C,B bits Access bits,domain

185. Address Space

188. Example

190. Kernel Address Space

195. Page Fault (COW)

206. VFS

207. USER PROCESSES SYSTEM CALL INTERFACE VFS Ext2 Ext3 DOS FS Buffer Cache Device Driver IO REQUEST HARDWARE Kernel