x86_64/vga: rely less on magic state

1 files changed, 19 insertions, 0 deletions

diff --git a/arch/x86_64/src/boot/entry64.s b/arch/x86_64/src/boot/entry64.s
index c5df5db..636e4cd 100644
--- a/arch/x86_64/src/boot/entry64.s
+++ b/arch/x86_64/src/boot/entry64.s
@@ -1,3 +1,16 @@
+.section .bss, "aw", @nobits
+
+//! A structure containing information gathered during the bootstrap process.
+//! Expected layout (as described by teachos::boot::information):
+//!
+//! struct
+//! {
+//!   multiboot2::information_view const * mbi;
+//!   std::size_t vga_buffer_index;
+//! }
+.global bootstrap_information
+bootstrap_information: .skip 16
+
 .section .boot_text, "ax", @progbits
 .code64
 
@@ -10,6 +23,12 @@ _entry64:
     mov %rax, %fs
     mov %rax, %gs
 
+    mov multiboot_information_pointer, %rax
+    mov vga_buffer_pointer, %rdx
+    sub $0xb8000, %rdx
+    mov %rax, (bootstrap_information)
+    mov %rdx, (bootstrap_information + 8)
+
     call invoke_global_constructors
     
     xor %rax, %rax