nintendoswitch: Add experimental Nintendo Switch support without CRT

Bare minimal nintendo switch support using LLD

targets/nintendoswitch.s

@@ -0,0 +1,51 @@
+.section .text.jmp, "x"
+.global _start
+_start:
+    b start
+    .word _mod_header - _start
+
+.section .data.mod0
+    .word 0, 8
+
+.global _mod_header
+_mod_header:
+    .ascii "MOD0"
+    .word __dynamic_start - _mod_header
+    .word __bss_start - _mod_header
+    .word __bss_end - _mod_header
+    .word 0, 0 // eh_frame_hdr start/end
+    .word 0 // runtime-generated module object offset
+
+.section .text, "x"
+.global start
+start:
+
+    // save lr
+    mov  x7, x30
+
+    // get aslr base
+    bl   +4
+    sub  x6, x30, #0x88
+
+    // context ptr and main thread handle
+    mov  x5, x0
+    mov  x4, x1
+
+    // clear .bss
+    adrp x5, __bss_start
+    add x5, x5, #:lo12:__bss_start
+    adrp x6, __bss_end
+    add x6, x6, #:lo12:__bss_end
+
+bssloop:
+    cmp x5, x6
+    b.eq run
+    str xzr, [x5]
+    add x5, x5, 8
+    b bssloop
+
+run:
+    // call entrypoint
+    adrp x30, exit
+    add  x30, x30, #:lo12:exit
+    b    main