/*
 * krane-fb-stub — minimal arm64 "hello framebuffer" payload for depthcharge.
 *
 * Entry contract (Linux arm64 boot protocol, verified against
 * linux/Documentation/arch/arm64/booting.rst and depthcharge
 * src/arch/arm/boot64.c + boot64_asm.S):
 *   - depthcharge copies the (uncompressed) kernel image to a random
 *     2 MiB-aligned slot in RAM, then jumps to its first byte with
 *     x0 = phys addr of flattened DTB, x1..x3 = 0, MMU off.
 *   - => everything must be position-independent (PC-relative only).
 *
 * 64-byte arm64 Image header (booting.rst):
 *   0x00 code0        b past header (this is where we are entered)
 *   0x04 code1        unused
 *   0x08 text_offset  0 (image sits AT the 2M-aligned base)
 *   0x10 image_size   patched by build.sh to the final file size
 *   0x18 flags        bit3 = "place anywhere in 48-bit range"
 *   0x20..0x37        reserved = 0
 *   0x38 magic        0x644d5241 "ARM\x64" (checked by depthcharge)
 *   0x3c res5         0
 */

	.section .head, "ax"
	.globl _start
_start:
	b	real_start		/* code0: branch to 0x40 */
	.word	0			/* code1 */
	.quad	0			/* text_offset */
	.quad	0			/* image_size — PATCHED by build.sh */
	.quad	1			/* flags: bit3 set (KASLR placement) */
	.quad	0			/* res2 */
	.quad	0			/* res3 */
	.quad	0			/* res4 */
	.word	0x644d5241		/* magic "ARM\x64" */
	.word	0			/* res5 */

	.section .text, "ax"
real_start:
	/* depthcharge's SP is dead; use our own stack inside the image */
	adrp	x4, stack_top
	add	x4, x4, :lo12:stack_top
	mov	sp, x4
	bl	cmain
1:	b	1b			/* cmain never returns; belt+braces halt */

	.section .stacksec, "aw"
	.align 4
	.globl stack_top
stack_bottom:
	.zero	16384
stack_top: