/*

 * Kernel startup entry point.

 * ---------------------------

 *

 * The requirements are:

 *   MMU = off, D-cache = off, I-cache = on or off,

 *   x0 = physical address to the FDT blob.

 *

 * This code is mostly position independent so you call this at

 * __pa(PAGE_OFFSET + TEXT_OFFSET).

 *

 * Note that the callee-saved registers are used for storing variables

 * that are useful before the MMU is enabled. The allocations are described

 * in the entry routines.

 */

              __HEAD

              /*

               * DO NOT MODIFY. Image header expected by Linux boot-loaders.

               */

#ifdef CONFIG_EFI

efi_head:

              /*

               * This add instruction has no meaningful effect except that

               * its opcode forms the magic "MZ" signature required by UEFI.

               */

              add       x13, x18, #0x16

              b            stext

#else

              b            stext                                               // branch to kernel start, magic

              .long    0                                                      // reserved

#endif

         __HEAD

ENTRY(stext)

 ……