Fix dmesg allocator

README.md

@@ -10,6 +10,7 @@ A kernel
 - Support RISC-V64, aarch64 and x86_64
 - Replace @import("root") with @import("main.zig") to allow for testing
 - Replace limine with a custom bootloader?
+- write core in zig and the rest in nov?
 
 # Clone, build and run
 Make sure to have `zig master`, `xorriso` and `qemu-system-x86` then run

kernel/debug.zig

@@ -17,15 +17,14 @@ const debug_allocator = debug_fba.allocator();
 var debug_info: ?std.debug.Dwarf = null;
 
 // https://github.com/ziglang/zig/issues/21233
-// var dmesg = blk: {
-//     var dmesg_sfa = std.heap.stackFallback(4096, root.allocator);
-//     break :blk std.ArrayList(u8).init(dmesg_sfa.get());
-// };
-var dmesg_fba_buffer: [1024 * 1024]u8 = undefined;
-var dmesg_fba = std.heap.FixedBufferAllocator.init(&dmesg_fba_buffer);
-var dmesg = std.ArrayList(u8).init(dmesg_fba.allocator());
+var dmesg_sfa = std.heap.stackFallback(4096, root.allocator);
+var dmesg: std.ArrayList(u8) = undefined;
 const dmesg_writer = dmesg.writer();
 
+pub fn init() void {
+    dmesg = std.ArrayList(u8).init(dmesg_sfa.get());
+}
+
 pub fn log(
     comptime level: std.log.Level,
     comptime scope: @TypeOf(.EnumLiteral),

kernel/main.zig

@@ -73,6 +73,7 @@ export fn _start() noreturn {
     arch.disableInterrupts();
 
     std.debug.assert(base_revision.is_supported());
+    debug.init();
     serial.init();
     arch.init();
     pmm.init();

kernel/mm/vmm.zig

@@ -18,7 +18,8 @@ const page_size = std.mem.page_size;
 
 // TODO: mapRange/unmapRange?
 // TODO: move paging code to paging.zig
-// TODO: use ArenaAllocator for vmm
+// TODO: use ArenaAllocator for vmm, especially where there is a lot of
+//       allocation in a loop or batch alloc/dealloc
 
 pub const MapError = error{
     OutOfMemory,

kernel/sched.zig

@@ -357,7 +357,7 @@ pub fn enqueue(thread: *Thread) !void {
         if (cpu.current_thread == null) {
             // only for debug build
             // fix to not crash when starting the first kernel thread
-            // if (comptime @import("builtin").mode == .Debug) {
+            // if (@import("builtin").mode == .Debug) {
             //     if (cpu.id == smp.thisCpu().id) continue;
             // }
 
@@ -415,7 +415,7 @@ fn schedHandler(ctx: *arch.Context) callconv(.SysV) void {
 
         current_thread.ctx = ctx.*;
 
-        if (comptime arch.arch == .x86_64) {
+        if (arch.arch == .x86_64) {
             current_thread.fs_base = arch.rdmsr(.fs_base);
             current_thread.cr3 = arch.readRegister("cr3");
             arch.cpu.fpuSave(current_thread.fpu_storage);
@@ -425,7 +425,7 @@ fn schedHandler(ctx: *arch.Context) callconv(.SysV) void {
     }
 
     if (maybe_next_thread) |next_thread| {
-        if (comptime arch.arch == .x86_64) {
+        if (arch.arch == .x86_64) {
             arch.wrmsr(.fs_base, next_thread.fs_base);
             cpu.current_thread = next_thread;