logger fixes

boot/main.c

@@ -76,12 +76,11 @@ void kernel_early_init() {
 
 [[noreturn]]
 void kernel_main(struct boot_info* info) {
-    // TODO: Initialize in-memory log ring.
-    kprintf("%s\n", zinnia_banner); // Say hello!
-    kprintf("Command line: %s\n", info->cmdline);
-
     cmdline_parse(info->cmdline);
 
+    log("%s\n", zinnia_banner); // Say hello!
+    log("Command line: %s\n", info->cmdline);
+
     initgraph_run(sched_stage, info);
 
     struct task* main_task;

core/console.c

@@ -13,10 +13,17 @@ void console_write(const char* buf, size_t len) {
     spin_unlock(&console_lock);
 }
 
+static void console_replay_write(void* ctx, const char* buf, size_t len) {
+    struct console* con = ctx;
+    con->write(con, buf, len);
+}
+
 bool console_register(struct console* con) {
     if (!con->init(con))
         return false;
 
+    con->write(con, "\ec", 2);
+    log_replay(console_replay_write, con);
     spin_lock(&console_lock);
     con->next = registered;
     registered = con;
@@ -37,8 +44,4 @@ void console_unregister(struct console* con) {
     spin_unlock(&console_lock);
 }
 
-[[__init]]
-static void console_stage_init(struct boot_info*) {
-    kprintf("\ec");
-}
-INIT_TASK(console_stage, "core.console", console_stage_init);
+INIT_TASK(console_stage, "core.console");

core/fbcon.c

@@ -26,6 +26,7 @@ enum esc_state {
 
 static struct {
     struct boot_framebuffer fb;
+    uint32_t* back;
     uint32_t fg, bg;
     size_t cols, rows;
     size_t offset_x, offset_y;
@@ -37,6 +38,15 @@ static inline uint8_t* fb_ptr() {
     return HHDM_PTR(fbcon.fb.base);
 }
 
+static inline uint32_t* back_row(size_t y) {
+    return fbcon.back + y * fbcon.fb.width;
+}
+
+static void flush_rect(size_t x, size_t y, size_t w, size_t h) {
+    for (size_t j = 0; j < h; j++)
+        memcpy((uint32_t*)(fb_ptr() + (y + j) * fbcon.fb.pitch) + x, back_row(y + j) + x, w * sizeof(uint32_t));
+}
+
 static uint32_t pack_color(uint32_t rgb) {
     const struct boot_framebuffer* fb = &fbcon.fb;
     uint32_t r = (rgb >> 16) & 0xff;
@@ -48,10 +58,11 @@ static uint32_t pack_color(uint32_t rgb) {
 
 static void fill_rect(size_t x, size_t y, size_t w, size_t h, uint32_t color) {
     for (size_t j = 0; j < h; j++) {
-        uint32_t* row = (uint32_t*)(fb_ptr() + (y + j) * fbcon.fb.pitch) + x;
+        uint32_t* row = back_row(y + j) + x;
         for (size_t i = 0; i < w; i++)
             row[i] = color;
     }
+    flush_rect(x, y, w, h);
 }
 
 static void clear_screen() {
@@ -65,19 +76,25 @@ static void draw_glyph(size_t col, size_t row, uint8_t ch) {
     size_t y = fbcon.offset_y + row * FONT_HEIGHT;
 
     for (size_t j = 0; j < FONT_HEIGHT; j++) {
-        uint32_t* line = (uint32_t*)(fb_ptr() + (y + j) * fbcon.fb.pitch) + x;
+        uint32_t* line = back_row(y + j) + x;
         for (size_t i = 0; i < FONT_WIDTH; i++)
             line[i] = (glyph[j] & (0x80 >> i)) ? fbcon.fg : fbcon.bg;
     }
+    flush_rect(x, y, FONT_WIDTH, FONT_HEIGHT);
 }
 
 static void scroll_up() {
-    const size_t pitch = fbcon.fb.pitch;
+    const size_t width = fbcon.fb.width;
     const size_t text_y = fbcon.offset_y;
     const size_t text_h = fbcon.rows * FONT_HEIGHT;
 
-    memmove(fb_ptr() + text_y * pitch, fb_ptr() + (text_y + FONT_HEIGHT) * pitch, (text_h - FONT_HEIGHT) * pitch);
-    fill_rect(0, text_y + text_h - FONT_HEIGHT, fbcon.fb.width, FONT_HEIGHT, fbcon.bg);
+    memmove(back_row(text_y), back_row(text_y + FONT_HEIGHT), (text_h - FONT_HEIGHT) * width * sizeof(uint32_t));
+    for (size_t j = text_y + text_h - FONT_HEIGHT; j < text_y + text_h; j++) {
+        uint32_t* row = back_row(j);
+        for (size_t i = 0; i < width; i++)
+            row[i] = fbcon.bg;
+    }
+    flush_rect(0, text_y, width, text_h);
 }
 
 static void newline() {
@@ -178,6 +195,10 @@ void fbcon_init(struct boot_info* info) {
             return;
     }
 
+    fbcon.back = mem_alloc(fb->width * fb->height * sizeof(uint32_t), ALLOC_NOZERO);
+    if (!fbcon.back)
+        return;
+
     console_register(&fbcon_con);
 }
 INIT_TASK(fbcon_stage, "core.fbcon", fbcon_init);

core/print.c

@@ -430,13 +430,39 @@ static const char* const log_level_colors[] = {
     [LOG_PANIC] = "\e[1;31m",
 };
 
-static void log_console_printf(const char* fmt, ...) {
+static void log_cb_printf(log_fn_t callback, void* ctx, const char* fmt, ...) {
     va_list args;
     va_start(args, fmt);
-    print_fmt(printf_console, nullptr, fmt, args);
+    print_fmt(callback, ctx, fmt, args);
     va_end(args);
 }
 
+// Formats a single record and passes it to `callback`.
+static void log_emit(log_fn_t callback, void* ctx, const struct log_record* rec, const char* msg) {
+    log_cb_printf(
+        callback,
+        ctx,
+        "[%5lu.%06lu] [%5lu] %s",
+        rec->time_ns / 1'000'000'000,
+        rec->time_ns / 1'000 % 1'000'000,
+        (uint64_t)rec->tid,
+        log_level_colors[rec->level]
+    );
+    callback(ctx, msg, rec->len);
+    callback(ctx, "\e[0m\n", 5);
+}
+
+void log_replay(log_fn_t callback, void* ctx) {
+    char msg[LOG_MESSAGE_MAX];
+    for (size_t offset = log_tail; offset != log_head;) {
+        struct log_record rec;
+        log_ring_peek(offset, &rec, sizeof(rec));
+        log_ring_peek(offset + sizeof(rec), msg, rec.len);
+        log_emit(callback, ctx, &rec, msg);
+        offset += sizeof(rec) + rec.len;
+    }
+}
+
 void log_vwrite(enum log_level level, const char* message, va_list args) {
     log_vwrite_prefixed(level, "", message, args);
 }
@@ -458,15 +484,7 @@ void log_vwrite_prefixed(enum log_level level, const char* prefix, const char* m
 
     spin_lock(&print_lock);
     log_store(&rec, line.buf);
-    log_console_printf(
-        "[%5lu.%06lu] [%5lu] %s",
-        rec.time_ns / 1'000'000'000,
-        rec.time_ns / 1'000 % 1'000'000,
-        (uint64_t)rec.tid,
-        log_level_colors[level]
-    );
-    console_write(line.buf, line.len);
-    console_write("\e[0m\n", 5);
+    log_emit(printf_console, nullptr, &rec, line.buf);
     spin_unlock(&print_lock);
 }
 

include/zinnia/print.h

@@ -34,6 +34,9 @@ void log_vwrite(enum log_level level, const char* message, va_list args);
 // Like log_vwrite(), but prepends a `prefix` to the message.
 void log_vwrite_prefixed(enum log_level level, const char* prefix, const char* message, va_list args);
 
+// Passes every record currently in the log buffer to `callback`.
+void log_replay(log_fn_t callback, void* ctx);
+
 #ifndef pr_fmt
 #define pr_fmt(fmt) fmt
 #endif