MM: add modules for memory management

8 files changed, 44 insertions, 0 deletions

diff --git a/src/arch/x86_64/asm/e820.s b/src/arch/x86_64/asm/e820.s
new file mode 100644
index 0000000..59c672a
--- /dev/null
+++ b/src/arch/x86_64/asm/e820.s
@@ -0,0 +1,2 @@
+; getting an E820 memory map, code from osdev wiki.
+; this only works in real mode ... how to do it in long mode?
diff --git a/src/arch/x86_64/linker.ld b/src/arch/x86_64/linker.ld
index 7a03770..ae77deb 100644
--- a/src/arch/x86_64/linker.ld
+++ b/src/arch/x86_64/linker.ld
@@ -71,4 +71,5 @@ SECTIONS
       *(".debug_aranges")
    }
 */
+    PROVIDE (KERNEL_END = .);
 }
diff --git a/src/arch/x86_64/mem.rs b/src/arch/x86_64/mem.rs
new file mode 100644
index 0000000..52ccdec
--- /dev/null
+++ b/src/arch/x86_64/mem.rs
@@ -0,0 +1,16 @@
+// to detect available memory to initialize PMA
+// https://wiki.osdev.org/Detecting_Memory_(x86)
+use core::arch::asm;
+use crate::io::*;
+
+extern "C" {
+	fn do_e820(start: usize) -> u32;
+}
+
+// Getting an E820 Memory Map -- osdev wiki
+pub fn prob_mem_bios(){
+	unsafe {
+		let res = do_e820(0x8000);
+		println!("res is {}", res)
+	}
+}
diff --git a/src/arch/x86_64/mod.rs b/src/arch/x86_64/mod.rs
index 9429c8f..c3b226e 100644
--- a/src/arch/x86_64/mod.rs
+++ b/src/arch/x86_64/mod.rs
@@ -2,3 +2,4 @@ pub mod cpu;
 pub mod interrupt;
 pub mod io_port;
 pub mod misc;
+pub mod mem;
diff --git a/src/defs.rs b/src/defs.rs
new file mode 100644
index 0000000..3c1ff57
--- /dev/null
+++ b/src/defs.rs
@@ -0,0 +1,13 @@
+pub struct Mem;
+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
+	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;
+}
diff --git a/src/lib.rs b/src/lib.rs
index 95a9455..b66afb5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,7 @@
 mod arch;
 mod io;
 mod machine;
+mod defs;
 use arch::x86_64::interrupt::pic_8259;
 use arch::x86_64::interrupt::pic_8259::PicDeviceInt;
 use core::panic::PanicInfo;
diff --git a/src/mm/mod.rs b/src/mm/mod.rs
new file mode 100644
index 0000000..1298d0d
--- /dev/null
+++ b/src/mm/mod.rs
@@ -0,0 +1 @@
+pub mod pma;
diff --git a/src/mm/pma.rs b/src/mm/pma.rs
new file mode 100644
index 0000000..f9a40ee
--- /dev/null
+++ b/src/mm/pma.rs
@@ -0,0 +1,9 @@
+use core::ffi::c_void;
+use crate::defs::Mem;
+// this is POC code, it will be ugly
+extern "C" {
+    static KERNEL_END: *const c_void;
+}
+
+// pub struct PageAlloctor;
+