From 3159a40bdb65f215f7ecce831998e8139e57cf02 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 17 Jul 2021 16:29:50 +0200
Subject: multiboot: manually address regions of the kernel
thanks to this, i can specify the region where the bss is - so GRUB
won't place any boot modules there
---
linker.ld | 1 +
src/arch/i386/multiboot.s | 20 ++++++++++++++------
2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/linker.ld b/linker.ld
index 92db365..d2aa8bd 100644
--- a/linker.ld
+++ b/linker.ld
@@ -16,6 +16,7 @@ SECTIONS
{
*(.data)
}
+ _data_end = .;
.bss BLOCK(4K) : ALIGN(4K)
{
*(COMMON)
diff --git a/src/arch/i386/multiboot.s b/src/arch/i386/multiboot.s
index 2194982..d67110f 100644
--- a/src/arch/i386/multiboot.s
+++ b/src/arch/i386/multiboot.s
@@ -1,11 +1,19 @@
.set MAGIC, 0x1BADB002
-.set FLAG_ALIGN, 1<<0 /* align modules on page boundaries */
-.set FLAG_MEMINFO, 1<<1 /* memory map */
-.set FLAGS, FLAG_ALIGN | FLAG_MEMINFO
+/* TODO set bss_end_addr, so the init module doesn't get overriden by the stack */
+
+/* 1<<0 - align modules on page boundaries.
+ 1<<16 - enable manual addressing */
+.set FLAGS, 1<<0 | 1<<16
.set CHECKSUM, -(MAGIC + FLAGS)
.section .multiboot
.align 4
-.long MAGIC
-.long FLAGS
-.long CHECKSUM
+multiboot_header:
+ .long MAGIC
+ .long FLAGS
+ .long CHECKSUM
+ .long multiboot_header // header_addr
+ .long multiboot_header // load_addr
+ .long _data_end // load_end_addr
+ .long _kernel_end // bss_end_addr
+ .long _start // entry_addr
--
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