linux_porting.pptVIP

Prerequisites Familiar with ARM architecture Basic understanding of Kernel internals Familiar with kernal build and config system Step by Step Machine Registration Bootloader requirements Early Kernel init Mapping I/O devices IRQ setup System timer tick Core subsystem initialization Final board initialization Device Drivers Machine registration Register your machine type Provides a unique numerical identifier for your machine Provides a configuration variable for your machine CONFIG_ARCH_XXX Provides runtime machine check machine_is_xxx() Http://.uk/developer/machines/ arch/arm/tools/mach-types Bootloader requirements Initialize all memory controller and system RAM Initialize a single serial port for early boot messages Disable MMU Disable all caches Provide kernel parameter ATAG list Required registers R0 = 0 R1 = machine number R2 = (ATAG list) ATAG Parameter List Data structure for providing machine details to kernel ATAG_CORE ATAG_MEM Memory size and locaton One per memory bank ... ATAG_CMDLINE ATAG_NONE ATAG defined in arch/arm/include/asm/setup.h Directory/File Structure arch/arm Mm Cache/TLB/page fault/DMA handling Kernel Core kernel setup, APIs, and system call Common Shared across various machine types Mach-xxx Machine specific Configs/XXX_defconfig Default configuration for XXX Related include file Early Init During decompressing kernel arch_decomp_setup() /* may be nothing */ Putc() Include/mach/uncompress.h Cpu Detection Large number of ARM CPU Each one has different methods of managing cache, TLB Kernel contains table of CPU it supports Arch/arm/mm/proc-$CPUTYPE Include/asm/procinfo.h First thing kernel does is check CPUID with table of CPUs Table contains a mask and expected value If (cpuid mask) == cpu_val ok , then call cpu_setup Low level CPU APIs Processor-specific functions Data abort, CPU init, reset, shutdown, idle Include/arm/cpu-multi32.h TLB handling Flush user and kernel TLB entries Include/arm/tlbflush.h (implemented in arch/ar