1. Mx6ull startup mode

6ull Support multiple external devices flash start-up

One , Start mode selection

The user manual says ： stay reset During this period, the chip will check the power supply control status register , Kernel behavior will receive boot mode pin The effect of setting .

During boot , The behavior of the core is defined by the boot mode pin settings , As described in the boot mode pin setting . When waking up from low power startup mode , The core will skip the clock setting . guide ROM Check PERSISTENT_ENTRY0( See persistent bit ） Whether it points to a valid address space (OCRAM、DDR、QSPI or EIM) The pointer to . If PERSISTENT_ENTRY0 Is a pointer to a valid range , Then it will use PERSISTENT_ENTRY0 The entry point in the register starts execution . If PERSISTENT_ENTRY0 Is a pointer to an invalid range , Then the core will perform a system reset .

Mainly 01 and 10 Two modes

10 When using Inside boot start-up

Start device selection （ When using internal boot Startup time ）

You need to choose which kind of startup device is flash equipment

( Longest use nand_FLASH SD EMMC QSPI_FLASH)

Two Start header file

1,boot rom Do the things

        Set the kernel clock to 396mhz. Can make mmu and Cache. Can make L1cache,L2cache MMU. The purpose is to speed up the startup .

        from boot_CFG Set in external storage , Read image, then Do the corresponding treatment .

2,IVT and BOOT data data

        Bin Add a header in front of the file , The header information includes the following .