From bef6d67f63125310dee0bb437175d660eaeab4a3 Mon Sep 17 00:00:00 2001
From: Tianhao Wang <wth@riseup.net>
Date: Sun, 25 Feb 2024 05:01:22 +0100
Subject: define memory layout (if there was a layout)

---
 src/arch/x86_64/linker.ld |  5 +++--
 src/defs.rs               | 40 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 40 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/arch/x86_64/linker.ld b/src/arch/x86_64/linker.ld
index ae77deb..b484366 100644
--- a/src/arch/x86_64/linker.ld
+++ b/src/arch/x86_64/linker.ld
@@ -46,7 +46,7 @@ SECTIONS
       *(".note.*")
    }
 
-   .bss : 
+   .bss :
    {
       ___BSS_START__ = .;
       *(".bss")
@@ -71,5 +71,6 @@ SECTIONS
       *(".debug_aranges")
    }
 */
-    PROVIDE (KERNEL_END = .);
+	. = ALIGN(4096);
+	PROVIDE (___KERNEL_END__ = .);
 }
diff --git a/src/defs.rs b/src/defs.rs
index 3c1ff57..cec17c9 100644
--- a/src/defs.rs
+++ b/src/defs.rs
@@ -1,13 +1,47 @@
 pub struct Mem;
+pub struct VAddr(u64);
+
 impl Mem {
 	// units
 	pub const K: usize = 1024;
 	pub const M: usize = 1024 * Mem::K;
 	pub const G: usize = 1024 * Mem::M;
-	// physical memory
-	pub const PHY_TOP: usize = 128 * Mem::M; // qemu defaults to 128 MiB phy Memory
+	// physical memory layout: qemu defaults to 128 MiB phy Memory
+	pub const PHY_TOP: usize = 128 * Mem::M;
+	// 4 lv 4K paging
 	pub const PAGE_SIZE: usize = 0x1000;
 	pub const PAGE_SHIFT: usize = 12;
-	pub const PHY_PAGES: usize = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
 	pub const PAGE_MASK: u64 = 0xfff;
+	pub const L0_SHIFT: u8 = 39;
+	pub const L0_MASK: u64 = 0x1ff << Mem::L0_SHIFT;
+	pub const L1_SHIFT: u8 = 30;
+	pub const L1_MASK: u64 = 0x1ff << Mem::L1_SHIFT;
+	pub const L2_SHIFT: u8 = 21;
+	pub const L2_MASK: u64 = 0x1ff << Mem::L2_SHIFT;
+	pub const L3_SHIFT: u8 = 12;
+	pub const L3_MASK: u64 = 0x1ff << Mem::L3_SHIFT;
+	pub const PHY_PAGES: usize = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
+	// size of frame allocator bitmap: number of physical frames / 8 for 128M
+	// memory (37268) 4k pages, 37268 bits are needed, hence
+	// 4096 bytes, exactly one page!
+	pub const PHY_BM_SIZE: usize = Mem::PHY_PAGES >> 3;
+}
+
+impl VAddr {
+	pub fn roundup_4k(&self) {
+		todo!()
+	}
+	pub fn rounddown_4k(&self) {
+		todo!()
+	}
+	pub fn page_number(&self) -> u64 {
+		self.0 >> Mem::PAGE_SHIFT
+	}
 }
+
+// PHY_TOP			128M
+// ~				free frames
+// PMA::bitmap		+ PHY_BM_SIZE
+// ~				___KERNEL_END__
+// KERNEL IMAGE
+// KERNEL START		1 M
-- 
cgit v1.2.3-70-g09d2