The kernel's handling of the device tree

< br>< div> kernel handling of the device tree < / div>< div> Linux Uses DT Data For Three Major Purposes: < / div>< div> 1) & have spentPlatform Identification, < / div>< div> 2) & have spentRuntime The configuration, & have spentAnd < / div>< div> 3) & have spentDevice Population. < / div>< div> _ _ the kernel from source analysis 01 section head. The S of the simple processing of DTB < / div>< div> bootloader start kernel, sets, r1, r2, three register < / div>< div> r0 general is set to 0;< / div>< div> r1 general Settings for the machine Id (in the use of this parameter is not used in the device tree);&nbsp;< / div>< div> r2 generally set the start of the ATAGS or DTB address < / div>< div> bootloader to kernel parameters passed there are two methods: < / div>< div> ATAGS Or & have spentDTB < / div>< div> for ATAGS transfer method, & have spentYou can refer to our & amp;quot;Graduating class video - write their own bootloader&quot;< / div>< div> from the www.100ask.net download page to open the baidu website so < / div>< div> 100 ask share all files < / div>< div> 006 _u - boot_ kernel _ the root file system (cohesion) during phase 1 _2 video < / div>< div> _ from 0 to write lesson 002 bootloader_ deeper understanding bootloader < / div>< div> a. & have spent__lookup_processor_type & have spent: & have spentThe use of assembly instructions to read CPU ID, & have spentAccording to the ID to find the corresponding proc_info_list structure (contains initialization function, the information of this kind of CPU) < / div>< div> b. & have spent__vet_atags & have spent&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; : & have spentDetermine whether there is any available ATAGS or DTB < / div>< div> c. & have spent__create_page_tables & have spent&nbsp; &nbsp;: & have spentCreate a page table, & have spentCreating a virtual address and physical address mapping < / div>< div> d. & have spent__enable_mmu & have spent&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: & have spentCan make MMU, & have spentLater will be using a virtual address < / div>< div> e. & have spent__mmap_switched & have spent&nbsp; &nbsp; &nbsp; &nbsp; : & have spentIn the above function will call __mmap_switched < / div>< div> f & have spentThe bootloader incoming r2 parameters, & have spentSaved to variables in __atags_pointer < / div>< div> g. & have spentC function called start_kernel < / div>< div> head. S/head - common. S &nbsp;: & amp;nbsp;< / div>< div> the r1 value from the bootloader, & have spentAssigned to the variables: C & have spent_ < / div>