all: rework source tree structure

src/sys/mm/private.zig

@@ -0,0 +1,41 @@
+const config = @import("config");
+pub const phys = @import("phys.zig");
+pub const pmap = @import("pmap.zig");
+pub const init = @import("init.zig");
+pub const heap = @import("heap.zig");
+pub const zone = @import("zone.zig");
+pub const PMap = pmap.PMap;
+pub const tlb = @import("tlb.zig");
+pub const balance = @import("balance.zig");
+
+const ke = @import("root").ke;
+const ex = @import("root").ex;
+
+pub const Space = struct {
+    pmap: PMap,
+    arena: ex.Arena,
+    lock: ke.Mutex,
+};
+
+pub const PfnList = extern struct {
+    head: u32,
+    tail: u32,
+};
+
+pub const PMapLevel = struct {
+    shift: u6,
+    mask: usize,
+    leaf: bool,
+};
+
+pub const impl = switch (config.arch) {
+    .amd64 => @import("amd64/impl.zig"),
+    .riscv64 => @import("riscv64/impl.zig"),
+    else => @compileError("unsupported architecture"),
+};
+
+pub var kernel_space: Space = .{
+    .pmap = undefined,
+    .arena = undefined,
+    .lock = undefined,
+};