Search notes:

arch/x86/kernel/vmlinux.lds.S

arch/x86/kernel/vmlinux.lds.S is preprocessed to the linker script arch/x86/kernel/vmlinux.lds.

ENTRY symbol

Depending on the value of CONFIG_X86_32, phys_startup_32 or phys_startup_64 is defined as ENTRY symbol:

#ifdef CONFIG_X86_32
OUTPUT_ARCH(i386)
ENTRY(phys_startup_32)
#else
OUTPUT_ARCH(i386:x86-64)
ENTRY(phys_startup_64)
#endif

phys_startup_xx

The value of CONFIG_X86_32 defines either phys_startup_32 or phys_startup_64:

#ifdef CONFIG_X86_32
	. = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
	phys_startup_32 = ABSOLUTE(startup_32 - LOAD_OFFSET);
#else
	. = __START_KERNEL;
	phys_startup_64 = ABSOLUTE(startup_64 - LOAD_OFFSET);
#endif

startup_32 is defined in arch/x86/kernel/head_32.S, startup_64 in arch/x86/kernel/head_64.S.

Index