Build original Ada port core, V client, and x86-64 boot milestone

boot/start.S

@@ -0,0 +1,83 @@
+/* Original Open Agila Multiboot v1 entry. QEMU x86-64/BIOS target only. */
+.section .multiboot,"a"
+.balign 4
+.long 0x1badb002
+.long 0x00000003
+.long -(0x1badb002 + 0x00000003)
+.section .text.boot,"ax"
+.code32
+.global _start
+.type _start,@function
+_start:
+    cli
+    cld
+    mov %eax, boot_magic
+    mov $stack_top, %esp
+    /* GRUB enters 32-bit protected mode. Map the first GiB with 2 MiB pages.
+       These writable executable boot mappings are NOT process isolation. */
+    mov $pdpt, %eax
+    or $3, %eax
+    mov %eax, pml4
+    mov $page_directory, %eax
+    or $3, %eax
+    mov %eax, pdpt
+    xor %ecx, %ecx
+1:
+    mov %ecx, %eax
+    shl $21, %eax
+    or $0x83, %eax
+    mov %eax, page_directory(,%ecx,8)
+    inc %ecx
+    cmp $512, %ecx
+    jne 1b
+    mov %cr4, %eax
+    or $0x20, %eax
+    mov %eax, %cr4
+    mov $pml4, %eax
+    mov %eax, %cr3
+    mov $0xc0000080, %ecx
+    rdmsr
+    or $0x100, %eax
+    wrmsr
+    lgdt gdt_pointer
+    mov %cr0, %eax
+    or $0x80000000, %eax
+    mov %eax, %cr0
+    ljmp $0x08, $long_mode
+.code64
+long_mode:
+    mov $0x10, %ax
+    mov %ax, %ds
+    mov %ax, %es
+    mov %ax, %ss
+    xor %eax, %eax
+    mov %ax, %fs
+    mov %ax, %gs
+    mov $stack_top, %rsp
+    xor %rbp, %rbp
+    mov boot_magic(%rip), %edi
+    call agila_boot_main
+2:  cli
+    hlt
+    jmp 2b
+.section .rodata,"a"
+.balign 8
+gdt:
+    .quad 0
+    .quad 0x00af9a000000ffff
+    .quad 0x00cf92000000ffff
+gdt_end:
+gdt_pointer:
+    .word gdt_end-gdt-1
+    .long gdt
+.section .bss,"aw",@nobits
+.balign 4
+boot_magic: .skip 4
+.balign 4096
+pml4: .skip 4096
+pdpt: .skip 4096
+page_directory: .skip 4096
+.balign 16
+stack_bottom: .skip 65536
+stack_top:
+.section .note.GNU-stack,"",@progbits