Scheduler returns to IDLE when.. idle.

Reviewed-on: #11

.gitignore

@@ -7,3 +7,7 @@ iso_root
 *.gch
 */*.gch
 */*/*.gch
+.gdb_history
+symbols.map
+symbols.S
+*.log

DOOM.txt

@@ -0,0 +1,24 @@
+up to doom:
+
+- Return from pedicel_main() normally (to idle)
+
+** Checkpoint: ring0 process working
+
+- VFS layer (open/read/write/...) with USTar filesystem (for initrd)
+
+** Checkpoint: files not linked to but accessible by the kernel
+
+- Ring3 memory mappings 
+- Ring3 privilege switch
+
+** Checkpoint: welcome to userland
+
+- Syscall interface
+- Implement syscalls needed for doom
+
+** Checkpoint: can run simple programs, ring 3, loaded from filesystem 
+
+- Properly handle the keyboard interrupt (keyboard buffer)
+- Port DOOMgeneric (few functions with Framebuffer/ticks/etc.)
+
+** Achievement: It runs doom!

Makefile

@@ -1,13 +1,16 @@
-SOURCES = src/boot/boot.c src/sched/scheduler.c src/sched/process.c src/mem/heap/kheap.c src/mem/paging/vmm.c src/mem/paging/paging.c src/mem/paging/pmm.c src/string/string.c src/io/kbd/ps2.c src/io/serial/serial.c src/io/term/printf.c src/io/term/term.c src/idt/idt.c src/mem/gdt/gdt.c src/mem/misc/utils.c src/time/timer.c src/kmain.c
+SOURCES = src/debug/misc.c src/io/term/flanterm_backends/fb.c src/io/term/flanterm.c src/debug/panic.c src/debug/stacktrace.c src/boot/boot.c src/sched/scheduler.c src/sched/process.c src/mem/heap/kheap.c src/mem/paging/vmm.c src/mem/paging/paging.c src/mem/paging/pmm.c src/string/string.c src/io/kbd/ps2.c src/io/serial/serial.c src/io/term/printf.c src/io/term/term.c src/idt/idt.c src/mem/gdt/gdt.c src/mem/misc/utils.c src/time/timer.c src/kmain.c
 
 PROBLEMATIC_FLAGS=-Wno-unused-parameter -Wno-unused-variable
 
 build:
 	rm -f *.o
 	x86_64-elf-gcc -g -c -Isrc $(SOURCES) $(PROBLEMATIC_FLAGS) -Wall -Wextra -std=gnu99 -nostdlib -ffreestanding -fno-stack-protector -fno-omit-frame-pointer -fno-stack-check -fno-PIC -ffunction-sections -fdata-sections -mcmodel=kernel
-	objcopy -O elf64-x86-64 -B i386 -I binary zap-light16.psf zap-light16.o
 	nasm -f elf64 src/idt/idt.S -o idt_stub.o
 	x86_64-elf-ld -o pepperk -T linker.ld *.o
+	nm -n pepperk | awk '$$2 ~ /[TtDdBbRr]/ {print $$1, $$3}' > symbols.map
+	python3 symbols.py
+	nasm -f elf64 symbols.S -o symbols.o
+	x86_64-elf-ld -o pepperk -T linker.ld *.o
 
 limine/limine:
 	rm -rf limine
@@ -32,11 +35,15 @@ build-iso: limine/limine build
 	./limine/limine bios-install pepper.iso
 
 debug:
-	qemu-system-x86_64 -drive file=pepper.iso -s -S -d int -no-reboot -no-shutdown &
+	/usr/bin/qemu-system-x86_64 -drive file=pepper.iso -s -S -d int -D qemu.log -no-reboot -no-shutdown &
 	gdb pepperk --command=debug.gdb
 
+debug2:
+	/usr/bin/qemu-system-x86_64 -drive file=pepper.iso -s -S -d int -no-reboot -no-shutdown &
+	pwndbg pepperk --command=debug.gdb
+
 run: build-iso
-	qemu-system-x86_64 -cdrom pepper.iso -serial stdio
+	/usr/bin/qemu-system-x86_64 -cdrom pepper.iso -serial stdio
 
 clean:
-	rm -rf *.o pepperk iso_root pepper.iso limine
+	rm -rf *.o symbols.map symbols.S pepperk iso_root pepper.iso limine

README.md

@@ -2,7 +2,7 @@
 
 ## Trying the kernel
 
-First install the dependencies: `sudo apt install xorriso make qemu-system`
+First install the dependencies: `sudo apt install python3 xorriso make qemu-system`
 
 Then, to compile the kernel and make an ISO image file: `make build-iso`
 To run it with QEMU, `make run`
@@ -41,8 +41,10 @@ PepperOS wouldn't be possible without the following freely-licensed software:
 
 - the [Limine](https://codeberg.org/Limine/Limine) portable bootloader
 - Marco Paland's freestanding [printf implementation](https://github.com/mpaland)
-- the [ZAP](https://www.zap.org.au/projects/console-fonts-zap/) PSF console fonts
+- Mintuski's [Flanterm](https://codeberg.org/Mintsuki/Flanterm) terminal emulator
 
 ...and without these amazing resources:
 
 - the [OSDev](https://osdev.org) wiki & forums
+- Intel 64 and IA-32 Architectures Software Developer's Manual
+- Documentation for the [GNU Compiler Collection](https://gcc.gnu.org/onlinedocs/gcc/)

debug.gdb

@@ -1,3 +1,7 @@
 target remote localhost:1234
 set disassembly-flavor intel
-display/8i $rip
+display/4i $rip
+
+# Trying to debug that flanterm page fault
+
+# b plot_char_unscaled_uncanvas if $rdi == 0 || $rsi == 0 || $rdx == 0 || $r10 == 0

src/config.h

@@ -10,12 +10,14 @@
 /* version */
 #define PEPPEROS_VERSION_MAJOR "0"
 #define PEPPEROS_VERSION_MINOR "0"
-#define PEPPEROS_VERSION_PATCH "1"
-#define PEPPEROS_SPLASH "pepperOS version "PEPPEROS_VERSION_MAJOR"."PEPPEROS_VERSION_MINOR"."PEPPEROS_VERSION_PATCH"\n"
+#define PEPPEROS_VERSION_PATCH "58"
+#define PEPPEROS_SPLASH "\x1b[38;5;196mPepperOS\x1b[0m version "PEPPEROS_VERSION_MAJOR"."PEPPEROS_VERSION_MINOR"."PEPPEROS_VERSION_PATCH"\n"
 
 /* process */
 #define PROCESS_NAME_MAX 64
 #define PROCESS_STACK_SIZE 0x10000 // 64kb
+#define PROCESS_BASE 0x400000
+#define PROCESS_STACK_BASE 0x1000000
 
 /* sched */
 // 1 tick = 1 ms => quantum = 10ms
@@ -25,9 +27,10 @@
 #define KERNEL_BASE 0xFFFFFFFF80000000ULL
 // 2 MB should be enough (as of now, the whole kernel ELF is around 75kb)
 #define KERNEL_SIZE 0x200000
+#define KERNEL_STACK_SIZE 65536
 
 /* heap */
-#define KHEAP_SIZE (16*1024*1024)
+#define KHEAP_SIZE (32*1024*1024)
 
 /* term */
 #define TERM_HISTORY_MAX_LINES 256

src/debug/misc.c

@@ -0,0 +1,61 @@
+#include <kernel.h>
+#include "limine.h"
+#include "string/string.h"
+
+extern struct boot_context boot_ctx;
+
+// Display the memmap so we see how the memory is laid out at handoff
+void memmap_display(struct limine_memmap_response* response)
+{
+	DEBUG("Got memory map from Limine: revision %u, %u entries", response->revision, response->entry_count);
+
+	for (size_t i=0; i<response->entry_count; i++)
+	{
+		struct limine_memmap_entry* entry = response->entries[i];
+		char type[32] = {0};
+		switch(entry->type)
+		{
+			case LIMINE_MEMMAP_USABLE:
+				strcpy(type, "USABLE");
+				break;
+			case LIMINE_MEMMAP_RESERVED:
+				strcpy(type, "RESERVED");
+				break;
+			case LIMINE_MEMMAP_ACPI_RECLAIMABLE:
+				strcpy(type, "ACPI_RECLAIMABLE");
+				break;
+			case LIMINE_MEMMAP_ACPI_NVS:
+				strcpy(type, "ACPI_NVS");
+				break;
+			case LIMINE_MEMMAP_BAD_MEMORY:
+				strcpy(type, "BAD_MEMORY");
+				break;
+			case LIMINE_MEMMAP_BOOTLOADER_RECLAIMABLE:
+				strcpy(type, "BOOTLOADER_RECLAIMABLE");
+				break;
+			case LIMINE_MEMMAP_KERNEL_AND_MODULES:
+				strcpy(type, "KERNEL_AND_MODULES");
+				break;
+			case LIMINE_MEMMAP_FRAMEBUFFER:
+				strcpy(type, "FRAMEBUFFER");
+				break;
+			default:
+				strcpy(type, "UNKNOWN");
+				break;
+		}
+		DEBUG("entry %02u: [0x%016x | %016u bytes] - %s", i, entry->base, entry->length, type);
+	}
+}
+
+// Display the HHDM
+void hhdm_display(struct limine_hhdm_response* hhdm)
+{
+	DEBUG("Got HHDM revision=%u offset=0x%p", hhdm->revision, hhdm->offset);
+}
+
+void boot_mem_display()
+{
+	memmap_display(boot_ctx.mmap);
+	hhdm_display(boot_ctx.hhdm);
+	DEBUG("kernel: phys_base=0x%p virt_base=0x%p", boot_ctx.kaddr->physical_base, boot_ctx.kaddr->virtual_base);
+}

src/debug/panic.c

@@ -0,0 +1,27 @@
+#include <stddef.h>
+#include "idt/idt.h"
+#include "io/serial/serial.h"
+#include "kernel.h"
+
+void panic(struct cpu_status_t* ctx, const char* str)
+{
+	CLEAR_INTERRUPTS;
+	if (ctx == NULL)
+	{
+		DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m Something went horribly wrong! (no cpu ctx)");
+		fctprintf((void*)&skputc, 0, "\x1b[38;5;231m\x1b[48;5;27m");
+		DIE_DEBUG(str);
+		fctprintf((void*)&skputc, 0, "\x1b[0m");
+		skputc('\r');
+		skputc('\n');
+		DEBUG("\x1b[38;5;231m\x1b[48;5;196mend Kernel panic - halting...\x1b[0m");
+		hcf();
+	}
+	DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m at rip=%p\r\nSomething went horribly wrong! (%s) vect=0x%.2x errcode=0x%x\n\rrax=%p rbx=%p rcx=%p rdx=%p\n\rrsi=%p rdi=%p  r8=%p  r9=%p\n\rr10=%p r11=%p r12=%p r13=%p\n\rr14=%p r15=%p\n\n\rflags=%p\n\rHalting...",
+		ctx->iret_rip,
+		str,
+		ctx->vector_number, ctx->error_code, ctx->rax, ctx->rbx, ctx->rcx, ctx->rdx, ctx->rsi, ctx->rdi,
+		ctx->r8, ctx->r9, ctx->r10, ctx->r11, ctx->r12, ctx->r13, ctx->r14, ctx->r15, ctx->iret_flags);
+	debug_stack_trace(100);
+	hcf();
+}

src/debug/stacktrace.c

@@ -0,0 +1,75 @@
+#include <stdint.h>
+#include "kernel.h"
+
+void debug_stack_trace(unsigned int max_frames)
+{
+    DEBUG("*** begin stack trace ***");
+    // Thanks GCC :)
+    uintptr_t* rbp = (uintptr_t*)__builtin_frame_address(0);
+
+    for (unsigned int frame=0; frame<max_frames && rbp != NULL; frame++)
+    {
+        // Return address, 1 word above saved rbp
+        uintptr_t rip = rbp[1];
+        uintptr_t offset = 0;
+        const char* name = debug_find_symbol(rip, &offset);
+        DEBUG("[%u] <0x%p> (%s+0x%x)", frame, (void*)rip, name, offset);
+
+        uintptr_t* next_rbp = (uintptr_t*)rbp[0];
+
+        // invalid rbp or we're at the end
+        if (next_rbp <= rbp || next_rbp == NULL)
+        {
+            break;
+        }
+
+        rbp = next_rbp;
+    }
+    DEBUG("*** end stack trace ***");
+}
+
+typedef struct
+{
+    uint64_t addr;
+    const char *name;
+} __attribute__((packed)) kernel_symbol_t;
+
+__attribute__((weak)) extern kernel_symbol_t symbol_table[];
+__attribute__((weak)) extern uint64_t symbol_count;
+
+// binary search
+const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset)
+{
+    if (!symbol_table || symbol_count == 0)
+    {
+        if (offset) *offset = 0;
+        return "???";
+    }
+
+    int low = 0, high = (int)symbol_count - 1;
+    int best = -1;
+
+    while (low <= high)
+    {
+        int mid = (low + high) / 2;
+        if (symbol_table[mid].addr <= rip)
+        {
+            best = mid;
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+    }
+
+    if (best != -1)
+    {
+        if (offset)
+        {
+            *offset = rip - symbol_table[best].addr;
+        }
+        return symbol_table[best].name;
+    }
+
+    if (offset) *offset = 0;
+    return "unknown";
+}

src/idt/idt.S

@@ -151,12 +151,13 @@ vector_7_handler:
 align 16
 vector_8_handler:
     ; No error code, we only push vector number
-    push qword 1
+    push qword 8
     jmp interrupt_stub
 
 ; Coprocessor Segment Overrun
 align 16
 vector_9_handler:
+    push qword 0
     push qword 9
     jmp interrupt_stub
 

src/idt/idt.c

@@ -13,6 +13,7 @@
 #include <stdbool.h>
 #include "sched/scheduler.h"
 #include "config.h"
+#include "sched/process.h"
 
 struct interrupt_descriptor idt[256];
 struct idtr idt_reg;
@@ -21,7 +22,7 @@ struct idtr idt_reg;
 extern char vector_0_handler[];
 
 // Timer ticks
-extern uint64_t ticks;
+extern volatile uint64_t ticks;
 
 void idt_set_entry(uint8_t vector, void* handler, uint8_t dpl)
 {
@@ -51,9 +52,8 @@ void idt_load(void* idt_addr)
 
 void idt_init()
 {
-    // We set 256 entries, but we have only the first few stubs.
-    // Undefined behavior?
-    for (size_t i=0; i<256; i++)
+    // Hardcoded...
+    for (size_t i=0; i<=33; i++)
     {
         // Each vector handler is 16-byte aligned, so <vector_no>*16 = address of that handler
         idt_set_entry(i, vector_0_handler + (i*16), 0);
@@ -87,11 +87,7 @@ static void page_fault_handler(struct cpu_status_t* ctx)
     CHECK_BIT(ctx->error_code, 7) ? " SGX_VIOLATION" : "",
     cr2);
 
-    /* if (CHECK_BIT(ctx->error_code, 0))
-    {
-        panic(ctx);
-    } */
-    panic(ctx);
+    panic(ctx, "page fault");
 }
 
 static void gp_fault_handler(struct cpu_status_t* ctx)
@@ -117,11 +113,16 @@ static void gp_fault_handler(struct cpu_status_t* ctx)
         index);
     }
 
-    panic(ctx);
+    panic(ctx, "gp fault");
 }
 
 struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
 {
+    if (context == NULL)
+    {
+        panic(NULL, "Interrupt dispatch recieved NULL context!");
+    }
+
     switch(context->vector_number)
     {
         case 0:
@@ -144,6 +145,7 @@ struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
             break;
         case 6:
             DEBUG("Invalid Opcode!");
+            panic(context, "Invalid Opcode!");
             break;
         case 7:
             DEBUG("Device Not Available!");
@@ -194,21 +196,20 @@ struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
 
         case 32: // Timer Interrupt
             ticks++;
+            // Send an EOI so that we can continue having interrupts
+            outb(0x20, 0x20);
 
             if (ticks % SCHEDULER_QUANTUM == 0)
             {
-                CLEAR_INTERRUPTS;
-                scheduler_schedule();
-                SET_INTERRUPTS;
+                return scheduler_schedule(context);
             }
 
-            // Send an EOI so that we can continue having interrupts
-            outb(0x20, 0x20);
             break;
 
         case 33:
             DEBUG("Keyboard Interrupt");
             keyboard_handler();
+            outb(0x20, 0x20);
             break;
 
         default:

src/io/kbd/ps2.c

@@ -17,6 +17,8 @@ uint8_t key_status = 0b00000000;
 unsigned char* keymap;
 unsigned char* keymap_shifted;
 
+extern struct init_status init;
+
 unsigned char kbdus[128] =
 {
     0,  27, '1', '2', '3', '4', '5', '6', '7', '8',	/* 9 */
@@ -176,9 +178,6 @@ void keyboard_handler()
                 key_status &= ~ALT_PRESSED_BIT;
                 break;
         }
-
-        // Send EOI
-        outb(0x20, 0x20);
         return;
     }
     else
@@ -199,21 +198,26 @@ void keyboard_handler()
                 break;
 
             default:
+            {
+                // Avoiding buffer overflow from extended keys lol
+                if (scancode < 128)
                 {
                     // Should we get a SHIFTED char or a regular one?
                     unsigned char c = (key_status & SHIFT_PRESSED_BIT) ? keymap_shifted[scancode] : keymap[scancode];
 
                     if (c)
                     {
+                        if (c == '\n')
+                        {
+                            _putchar('\r');
+                        }
                         // Should probably have a keyboard buffer here... instead of this
-                    putchar(c);
+                        _putchar(c);
+                    }
                 }
             }
         }
     }
-
-    // End of Interrupt (to master PIC)
-    outb(0x20, 0x20);
 }
 
 void keyboard_init(unsigned char layout)
@@ -233,14 +237,21 @@ void keyboard_init(unsigned char layout)
             break;
         
         default:
-            skputs("Unsupported layout.");
+            panic(NULL, "Unsupported keyboard layout");
             return;
     }
 
+    // Flush keyboard buffer
+    while (inb(0x64) & 1)
+    {
+        inb(0x60);
+    }
+
     // Unmask IRQ1
     uint8_t mask = inb(0x21);
     mask &= ~(1 << 1);
     outb(0x21, mask);
 
     DEBUG("PS/2 Keyboard initialized");
+    init.keyboard = true;
 }

src/io/serial/serial.c

@@ -7,6 +7,8 @@
 #include <kernel.h>
 #include "serial.h"
 
+extern struct init_status init;
+
 void outb(int port, unsigned char data)
 {
     __asm__ __volatile__("outb %%al, %%dx" :: "a" (data),"d" (port));
@@ -42,7 +44,8 @@ int serial_init()
     // Set normal operation mode
     outb(PORT + 4, 0x0F);
 
-    DEBUG("serial initialized");
+    DEBUG("*** Welcome to PepperOS! ***");
+    init.serial = true;
     return 0;
 }
 
@@ -54,6 +57,7 @@ static int is_transmit_empty()
 // Serial kernel putchar
 void skputc(char c)
 {
+    // TODO: Spinlock here (serial access)
     while (!is_transmit_empty()); // wait for free spot
     outb(PORT, c);
 }

src/io/term/flanterm.h

@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_H
+#define FLANTERM_H 1
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_CB_DEC 10
+#define FLANTERM_CB_BELL 20
+#define FLANTERM_CB_PRIVATE_ID 30
+#define FLANTERM_CB_STATUS_REPORT 40
+#define FLANTERM_CB_POS_REPORT 50
+#define FLANTERM_CB_KBD_LEDS 60
+#define FLANTERM_CB_MODE 70
+#define FLANTERM_CB_LINUX 80
+#define FLANTERM_CB_OSC 90
+
+#ifdef FLANTERM_IN_FLANTERM
+
+#include "flanterm_private.h"
+
+#else
+
+struct flanterm_context;
+
+#endif
+
+void flanterm_write(struct flanterm_context *ctx, const char *buf, size_t count);
+void flanterm_flush(struct flanterm_context *ctx);
+void flanterm_full_refresh(struct flanterm_context *ctx);
+void flanterm_deinit(struct flanterm_context *ctx, void (*_free)(void *ptr, size_t size));
+
+void flanterm_get_dimensions(struct flanterm_context *ctx, size_t *cols, size_t *rows);
+void flanterm_set_autoflush(struct flanterm_context *ctx, bool state);
+void flanterm_set_callback(struct flanterm_context *ctx, void (*callback)(struct flanterm_context *, uint64_t, uint64_t, uint64_t, uint64_t));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/io/term/flanterm_backends/fb.h

@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_FB_H
+#define FLANTERM_FB_H 1
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "../flanterm.h"
+
+#ifdef FLANTERM_IN_FLANTERM
+
+#include "fb_private.h"
+
+#endif
+
+#define FLANTERM_FB_ROTATE_0 0
+#define FLANTERM_FB_ROTATE_90 1
+#define FLANTERM_FB_ROTATE_180 2
+#define FLANTERM_FB_ROTATE_270 3
+
+struct flanterm_context *flanterm_fb_init(
+    /* If _malloc and _free are nulled, use the bump allocated instance (1 use only). */
+    void *(*_malloc)(size_t size),
+    void (*_free)(void *ptr, size_t size),
+    uint32_t *framebuffer, size_t width, size_t height, size_t pitch,
+    uint8_t red_mask_size, uint8_t red_mask_shift,
+    uint8_t green_mask_size, uint8_t green_mask_shift,
+    uint8_t blue_mask_size, uint8_t blue_mask_shift,
+    uint32_t *canvas, /* If nulled, no canvas. */
+    uint32_t *ansi_colours, uint32_t *ansi_bright_colours, /* If nulled, default. */
+    uint32_t *default_bg, uint32_t *default_fg, /* If nulled, default. */
+    uint32_t *default_bg_bright, uint32_t *default_fg_bright, /* If nulled, default. */
+    /* If font is null, use default font and font_width and font_height ignored. */
+    void *font, size_t font_width, size_t font_height, size_t font_spacing,
+    /* If scale_x and scale_y are 0, automatically scale font based on resolution. */
+    size_t font_scale_x, size_t font_scale_y,
+    size_t margin,
+    /* One of FLANTERM_FB_ROTATE_* values. */
+    int rotation
+);
+
+void flanterm_fb_set_flush_callback(struct flanterm_context *ctx, void (*flush_callback)(volatile void *address, size_t length));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/io/term/flanterm_backends/fb_private.h

@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_FB_PRIVATE_H
+#define FLANTERM_FB_PRIVATE_H 1
+
+#ifndef FLANTERM_IN_FLANTERM
+#error "Do not use fb_private.h. Use interfaces defined in fb.h only."
+#endif
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_FB_FONT_GLYPHS 256
+
+struct flanterm_fb_char {
+    uint32_t c;
+    uint32_t fg;
+    uint32_t bg;
+};
+
+struct flanterm_fb_queue_item {
+    size_t x, y;
+    struct flanterm_fb_char c;
+};
+
+struct flanterm_fb_context {
+    struct flanterm_context term;
+
+    void (*plot_char)(struct flanterm_context *ctx, struct flanterm_fb_char *c, size_t x, size_t y);
+    void (*flush_callback)(volatile void *address, size_t length);
+
+    size_t font_width;
+    size_t font_height;
+    size_t glyph_width;
+    size_t glyph_height;
+
+    size_t font_scale_x;
+    size_t font_scale_y;
+
+    size_t offset_x, offset_y;
+
+    volatile uint32_t *framebuffer;
+    size_t pitch;
+    size_t width;
+    size_t height;
+    size_t phys_height;
+    size_t bpp;
+
+    uint8_t red_mask_size, red_mask_shift;
+    uint8_t green_mask_size, green_mask_shift;
+    uint8_t blue_mask_size, blue_mask_shift;
+
+    int rotation;
+
+    size_t font_bits_size;
+    uint8_t *font_bits;
+    size_t font_bool_size;
+    bool *font_bool;
+
+    uint32_t ansi_colours[8];
+    uint32_t ansi_bright_colours[8];
+    uint32_t default_fg, default_bg;
+    uint32_t default_fg_bright, default_bg_bright;
+
+    size_t canvas_size;
+    uint32_t *canvas;
+
+    size_t grid_size;
+    size_t queue_size;
+    size_t map_size;
+
+    struct flanterm_fb_char *grid;
+
+    struct flanterm_fb_queue_item *queue;
+    size_t queue_i;
+
+    struct flanterm_fb_queue_item **map;
+
+    uint32_t text_fg;
+    uint32_t text_bg;
+    size_t cursor_x;
+    size_t cursor_y;
+
+    uint32_t saved_state_text_fg;
+    uint32_t saved_state_text_bg;
+    size_t saved_state_cursor_x;
+    size_t saved_state_cursor_y;
+
+    size_t old_cursor_x;
+    size_t old_cursor_y;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/io/term/flanterm_private.h

@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_PRIVATE_H
+#define FLANTERM_PRIVATE_H 1
+
+#ifndef FLANTERM_IN_FLANTERM
+#error "Do not use flanterm_private.h. Use interfaces defined in flanterm.h only."
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_MAX_ESC_VALUES 16
+
+struct flanterm_context {
+    /* internal use */
+
+    size_t tab_size;
+    bool autoflush;
+    bool cursor_enabled;
+    bool scroll_enabled;
+    bool wrap_enabled;
+    bool origin_mode;
+    bool control_sequence;
+    bool escape;
+    bool osc;
+    bool osc_escape;
+    size_t osc_buf_i;
+    uint8_t osc_buf[256];
+    bool rrr;
+    bool discard_next;
+    bool bold;
+    bool bg_bold;
+    bool reverse_video;
+    bool dec_private;
+    bool insert_mode;
+    bool csi_unhandled;
+    uint64_t code_point;
+    size_t unicode_remaining;
+    uint8_t g_select;
+    uint8_t charsets[2];
+    size_t current_charset;
+    size_t escape_offset;
+    size_t esc_values_i;
+    size_t saved_cursor_x;
+    size_t saved_cursor_y;
+    size_t current_primary;
+    size_t current_bg;
+    size_t scroll_top_margin;
+    size_t scroll_bottom_margin;
+    uint32_t esc_values[FLANTERM_MAX_ESC_VALUES];
+    uint8_t last_printed_char;
+    bool last_was_graphic;
+    bool saved_state_bold;
+    bool saved_state_bg_bold;
+    bool saved_state_reverse_video;
+    bool saved_state_origin_mode;
+    bool saved_state_wrap_enabled;
+    size_t saved_state_current_charset;
+    uint8_t saved_state_charsets[2];
+    size_t saved_state_current_primary;
+    size_t saved_state_current_bg;
+
+    /* to be set by backend */
+
+    size_t rows, cols;
+
+    void (*raw_putchar)(struct flanterm_context *, uint8_t c);
+    void (*clear)(struct flanterm_context *, bool move);
+    void (*set_cursor_pos)(struct flanterm_context *, size_t x, size_t y);
+    void (*get_cursor_pos)(struct flanterm_context *, size_t *x, size_t *y);
+    void (*set_text_fg)(struct flanterm_context *, size_t fg);
+    void (*set_text_bg)(struct flanterm_context *, size_t bg);
+    void (*set_text_fg_bright)(struct flanterm_context *, size_t fg);
+    void (*set_text_bg_bright)(struct flanterm_context *, size_t bg);
+    void (*set_text_fg_rgb)(struct flanterm_context *, uint32_t fg);
+    void (*set_text_bg_rgb)(struct flanterm_context *, uint32_t bg);
+    void (*set_text_fg_default)(struct flanterm_context *);
+    void (*set_text_bg_default)(struct flanterm_context *);
+    void (*set_text_fg_default_bright)(struct flanterm_context *);
+    void (*set_text_bg_default_bright)(struct flanterm_context *);
+    void (*move_character)(struct flanterm_context *, size_t new_x, size_t new_y, size_t old_x, size_t old_y);
+    void (*scroll)(struct flanterm_context *);
+    void (*revscroll)(struct flanterm_context *);
+    void (*swap_palette)(struct flanterm_context *);
+    void (*save_state)(struct flanterm_context *);
+    void (*restore_state)(struct flanterm_context *);
+    void (*double_buffer_flush)(struct flanterm_context *);
+    void (*full_refresh)(struct flanterm_context *);
+    void (*deinit)(struct flanterm_context *, void (*)(void *, size_t));
+
+    /* to be set by client */
+
+    void (*callback)(struct flanterm_context *, uint64_t, uint64_t, uint64_t, uint64_t);
+};
+
+void flanterm_context_reinit(struct flanterm_context *ctx);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/io/term/term.c

@@ -11,196 +11,23 @@ because this shitty implementation will be replaced one day by Flanterm
 (once memory management is okay: paging & kernel malloc)
 */
 
-#include <limine.h>
 #include <stddef.h>
 #include <kernel.h>
 #include "term.h"
-#include "mem/misc/utils.h"
 #include "config.h"
+#include "flanterm.h"
+#include "flanterm_backends/fb.h"
+#include "mem/heap/kheap.h"
+#include "limine.h"
 
-extern struct boot_context boot_ctx;
-
-// Importing the PSF object file
-extern unsigned char _binary_zap_light16_psf_start[];
-extern unsigned char _binary_zap_light16_psf_end[];
-
-PSF1_Header* font = (PSF1_Header*)_binary_zap_light16_psf_start;
-uint8_t* glyphs = _binary_zap_light16_psf_start + sizeof(PSF1_Header);
-
-#define FONT_WIDTH 8
-#define FONT_HEIGHT font->characterSize
-
-
-
-// Character cursor
-typedef struct
-{
-	size_t x;
-	size_t y;
-} Cursor;
-
-static Cursor cursor = {0, 0};
-
-static uint8_t* fb;
-static struct limine_framebuffer* framebuffer;
-
-uint8_t lines_length[TERM_HISTORY_MAX_LINES];
-
-static inline size_t term_max_cols(void)
-{
-	return framebuffer->width / FONT_WIDTH;
-}
-
-static inline size_t term_max_lines(void)
-{
-	return framebuffer->height / FONT_HEIGHT;
-}
-
-int term_init()
-{
-	// Get framebuffer address from Limine struct
-	
-	if (!boot_ctx.fb)
-	{
-		return -ENOMEM;
-	}
-
-	framebuffer = boot_ctx.fb;
-	fb = (uint8_t*)framebuffer->address;
-
-	memset(lines_length, 0, sizeof(lines_length));
-
-	DEBUG("terminal initialized, fb=0x%p (width=%u height=%u pitch=%u bpp=%u)", fb, framebuffer->width, framebuffer->height, framebuffer->pitch, framebuffer->bpp);
-	return 0;
-}
-
-// These are marked "static" because we don't wanna expose them all around
-// AKA they should just be seen here (kind of like private functions in cpp)
-static inline void putpixel(size_t x, size_t y, uint32_t color)
-{
-	// Guard so we don't write past fb boundaries
-	if (x >= framebuffer->width || y >= framebuffer->height) return;
-	// Depth isn't part of limine_framebuffer attributes so it will be 4
-	size_t pos = x*4 + y*framebuffer->pitch;
-	fb[pos] = color & 255; // blue channel
-	fb[pos+1] = (color >> 8) & 255; // green
-	fb[pos+2] = (color >> 16) & 255; // blue
-}
-
-static void draw_char(char c, size_t px, size_t py, uint32_t fg, uint32_t bg)
-{
-	// So we cannot write past fb
-	if (px+FONT_WIDTH > framebuffer->width || py+FONT_HEIGHT > framebuffer->height) return;
-
-	uint8_t* glyph = glyphs + ((unsigned char)c * FONT_HEIGHT);
-
-	for (size_t y=0; y<FONT_HEIGHT; y++)
-	{
-		uint8_t row = glyph[y];
-		for (size_t x=0; x<FONT_WIDTH; x++)
-		{
-			uint32_t color = (row & (0x80 >> x)) ? fg : bg;
-			putpixel(px+x, py+y, color);
-		}
-	}
-}
-
-static void erase_char(size_t px, size_t py)
-{
-	if (px+FONT_WIDTH > framebuffer->width || py+FONT_HEIGHT > framebuffer->height) return;
-
-	for (size_t y=0; y<FONT_HEIGHT; y++)
-	{
-		for (size_t x=0; x<FONT_WIDTH; x++)
-		{
-			// Black
-			putpixel(px+x, py+y, 0);
-		}
-	}
-}
-
-void term_scroll()
-{
-	// Erase first text line
-	memset(fb, 255, FONT_HEIGHT*framebuffer->pitch);
-
-	// Move whole framebuffer up by one text line
-	memmove(fb, fb+(FONT_HEIGHT*framebuffer->pitch), (framebuffer->height-FONT_HEIGHT)*framebuffer->pitch);
-
-	// Clear last text line
-	size_t clear_start = (framebuffer->height - FONT_HEIGHT) * framebuffer->pitch;
-	memset(fb + clear_start, 255, FONT_HEIGHT * framebuffer->pitch);
-
-	// Shift line lengths by 1 (for backspace handling)
-	size_t max_lines = term_max_lines();
-	for (size_t i = 1; i < max_lines; i++)
-	{
-		lines_length[i - 1] = lines_length[i];
-	}
-	lines_length[max_lines - 1] = 0;
-}
-
-void putchar(char c)
-{
-	const size_t max_cols = term_max_cols();
-	const size_t max_lines = term_max_lines();
-
-	if (c == '\n') {
-		lines_length[cursor.y] = cursor.x;
-		cursor.x = 0;
-
-		if (cursor.y + 1 >= max_lines)
-		{
-			term_scroll();
-		}
-		else
-		{
-			cursor.y++;
-		}
-		return;
-	}
-
-	if (c == '\b') 
-	{
-		if (cursor.x > 0) 
-		{
-			cursor.x--;
-		}
-		else if (cursor.y > 0)
-		{
-			cursor.y--;
-			cursor.x = lines_length[cursor.y];
-		}
-		else
-		{
-			return;
-		}
-
-		erase_char(cursor.x * FONT_WIDTH, cursor.y * FONT_HEIGHT);
-		return;
-	}
-
-	if (cursor.x >= max_cols) 
-	{
-		cursor.x = 0;
-		if (cursor.y + 1 >= max_lines)
-		{
-			term_scroll();
-		}
-		else
-		{
-			cursor.y++;
-		}
-	}
-
-	draw_char(c, cursor.x * FONT_WIDTH, cursor.y * FONT_HEIGHT, WHITE, BLACK);
-	cursor.x++;
-}
+extern struct flanterm_context* ft_ctx;
+extern struct init_status init;
 
 // Overhead that could be avoided, right? (for printf)
 void _putchar(char character)
 {
-	putchar(character);
+	// TODO: Spinlock here (terminal access)
+	flanterm_write(ft_ctx, &character, 1);
 }
 
 // Debug-printing
@@ -209,7 +36,39 @@ void kputs(const char* str)
 	size_t i=0;
 	while (str[i] != 0)
 	{
-		putchar(str[i]);
+		_putchar(str[i]);
 		i++;
 	}
+	_putchar('\r');
+}
+
+extern struct flanterm_context* ft_ctx;
+extern struct boot_context boot_ctx;
+
+void flanterm_free_wrapper(void* ptr, size_t size)
+{
+	(void)size;
+	kfree(ptr);
+}
+
+void term_init()
+{
+	uint32_t bgColor = 0x252525;
+	ft_ctx = flanterm_fb_init(
+        kmalloc,
+        flanterm_free_wrapper,
+        boot_ctx.fb->address, boot_ctx.fb->width, boot_ctx.fb->height, boot_ctx.fb->pitch,
+        boot_ctx.fb->red_mask_size, boot_ctx.fb->red_mask_shift,
+        boot_ctx.fb->green_mask_size, boot_ctx.fb->green_mask_shift,
+        boot_ctx.fb->blue_mask_size, boot_ctx.fb->blue_mask_shift,
+        NULL,
+        NULL, NULL,
+        &bgColor, NULL,
+        NULL, NULL,
+        NULL, 0, 0, 1,
+        0, 0,
+        0,
+        0
+    );
+	init.terminal = true;
 }

src/io/term/term.h

@@ -7,26 +7,8 @@
 #ifndef TERM_H
 #define TERM_H
 
-int term_init();
 void kputs(const char* str);
-void putchar(char c);
-
-enum TermColors
-{
-    BLACK = 0x000000,
-    WHITE = 0xffffff
-};
-
-#define PSF1_FONT_MAGIC 0x0436
-
-typedef struct
-{
-    uint16_t magic;
-    uint8_t fontMode;
-    uint8_t characterSize; // height
-} PSF1_Header;
-
-// debug 
-void term_scroll();
+void _putchar(char character);
+void term_init();
 
 #endif

src/kernel.h

@@ -19,15 +19,32 @@ enum ErrorCodes
 #include "io/serial/serial.h"
 #include "io/term/printf.h"
 #include "idt/idt.h"
+#include <stdbool.h>
 
-#define DEBUG(log, ...) fctprintf((void*)&skputc, 0, "debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__)
+extern volatile uint64_t ticks;
+
+#define DEBUG(log, ...) fctprintf((void*)&skputc, 0, "[%8u] debug: <%s>: " log "\r\n", ticks, __func__, ##__VA_ARGS__)
+
+/* #define DEBUG(log, ...) \
+	printf("debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__); \
+	fctprintf((void*)&skputc, 0, "debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__)
+ */
+
+#define DIE_DEBUG(str) fctprintf((void*)&skputc, 0, str)
 
 #define CHECK_BIT(var,pos) ((var) & (1<<(pos)))
 
 // printf("debug: [%s]: " log "\n", __FILE__, ##__VA_ARGS__);
 
-void panic(struct cpu_status_t* ctx);
+void panic(struct cpu_status_t* ctx, const char* str);
 void hcf();
+void idle();
+
+/* debug */
+void debug_stack_trace(unsigned int max_frames);
+const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset);
+void boot_mem_display();
+
 #define assert(check) do { if(!(check)) hcf(); } while(0)
 
 struct boot_context
@@ -38,4 +55,13 @@ struct boot_context
 	struct limine_kernel_address_response* kaddr;
 };
 
+// Are these modules initialized yet?
+struct init_status
+{
+	bool terminal;
+	bool serial;
+	bool keyboard;
+	bool timer;
+};
+
 #endif

src/kmain.c

@@ -23,6 +23,8 @@
 #include "sched/process.h"
 #include "sched/scheduler.h"
 #include "config.h"
+#include "io/term/flanterm.h"
+#include "io/term/flanterm_backends/fb.h"
 
 // Limine version used
 __attribute__((used, section(".limine_requests")))
@@ -35,19 +37,11 @@ void hcf()
 }
 
 // Doing nothing (can be interrupted)
-void idle() {for(;;)asm("hlt");}
-
-void panic(struct cpu_status_t* ctx)
-{
-	DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m at rip=%p\nSomething went horribly wrong! vect=0x%.2x errcode=0x%x\n\rrax=%p rbx=%p rcx=%p rdx=%p\n\rrsi=%p rdi=%p  r8=%p  r9=%p\n\rr10=%p r11=%p r12=%p r13=%p\n\rr14=%p r15=%p\n\n\rflags=%p\n\rstack at rbp=%p\n\rHalting...",
-		ctx->iret_rip,
-		ctx->vector_number, ctx->error_code, ctx->rax, ctx->rbx, ctx->rcx, ctx->rdx, ctx->rsi, ctx->rdi,
-		ctx->r8, ctx->r9, ctx->r10, ctx->r11, ctx->r12, ctx->r13, ctx->r14, ctx->r15, ctx->iret_flags,
-		ctx->rbp);
-	hcf();
-}
+void idle() {SET_INTERRUPTS; for(;;)asm("hlt");}
 
+struct flanterm_context *ft_ctx;
 struct boot_context boot_ctx;
+struct init_status init = {0};
 
 extern volatile struct limine_framebuffer_request framebuffer_request;
 extern volatile struct limine_memmap_request memmap_request;
@@ -56,65 +50,65 @@ extern volatile struct limine_kernel_address_request kerneladdr_request;
 
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
+struct process_t* idle_proc;
 
+bool iran = false;
+
+// Never gets executed although pedicel is scheduled?
 void pedicel_main(void* arg)
 {
-	
+	bool iran = true;
+	// FROM THE NEXT LINE ONWARDS, CANNOT WRITE TO FRAMEBUFFER WITHOUT PAGE FAULT!
+	//printf("\n\nWelcome to PepperOS! Pedicel speaking.\nNothing left to do, halting the system!");
 }
 
-void two_main(void* arg)
+void idle_main(void* arg)
 {
-
-}
-
-void three_main(void* arg)
+	for (;;)
 	{
-
+		asm("hlt");
 	}
+}
+
+extern uintptr_t kheap_start;
 
 // This is our entry point
 void kmain()
 {
+	CLEAR_INTERRUPTS;
 	if (!LIMINE_BASE_REVISION_SUPPORTED) hcf();
 
+	serial_init();
+	timer_init();
+
 	// Populate boot context
  	boot_ctx.fb = framebuffer_request.response ? framebuffer_request.response->framebuffers[0] : NULL;
 	boot_ctx.mmap = memmap_request.response ? memmap_request.response : NULL;
 	boot_ctx.hhdm = hhdm_request.response ? hhdm_request.response : NULL;
 	boot_ctx.kaddr = kerneladdr_request.response ? kerneladdr_request.response : NULL;
 
-	serial_init();
-
-	memmap_display(boot_ctx.mmap);
-	hhdm_display(boot_ctx.hhdm);
-	DEBUG("kernel: phys_base=0x%p virt_base=0x%p", boot_ctx.kaddr->physical_base, boot_ctx.kaddr->virtual_base);
-
-	CLEAR_INTERRUPTS;
-	gdt_init();
-	idt_init();
-	timer_init();
-
+	boot_mem_display();
 	pmm_init(boot_ctx.mmap, boot_ctx.hhdm);
 
 	// Remap kernel , HHDM and framebuffer
 	paging_init(boot_ctx.kaddr, boot_ctx.fb);
-	
 	kheap_init();
 
-	vmm_init();
+	keyboard_init(FR);
 
+	term_init();
+
+	gdt_init();
+	idt_init();
+	
+	process_init();
+	idle_proc = process_create("idle", (void*)idle_main, 0);
 	struct process_t* pedicel = process_create("pedicel", (void*)pedicel_main, 0);
-	struct process_t* two = process_create("two", (void*)two_main, 0);
-	struct process_t* three = process_create("three", (void*)three_main, 0);
+
 	process_display_list(processes_list);
 
 	scheduler_init();
 
-	SET_INTERRUPTS;
-
-	keyboard_init(FR);
-	term_init();
 	kputs(PEPPEROS_SPLASH);
-
 	idle();
 }

src/mem/heap/kheap.c

@@ -23,40 +23,36 @@ static uintptr_t end;
 // Kernel root table (level 4)
 extern uint64_t *kernel_pml4;
 
-static void kheap_grow(size_t size)
-{
-    size_t pages = ALIGN_UP(size + sizeof(struct heap_block_t), PAGE_SIZE) / PAGE_SIZE;
-    
-    if (pages == 0) pages = 1;
-    
-    for (size_t i = 0; i < pages; i++)
-    {
-        kheap_map_page();
-    }
-}
-
-void kheap_map_page()
-{
-    uintptr_t phys = pmm_alloc();
-    paging_map_page(kernel_pml4, end, phys, PTE_PRESENT | PTE_WRITABLE | PTE_NOEXEC);
-    end += PAGE_SIZE;
-    //DEBUG("Mapped first kheap page");
-}
-
 void kheap_init()
 {
     kheap_start = ALIGN_UP(kernel_virt_base + KERNEL_SIZE, PAGE_SIZE);
-    end = kheap_start;
     
-    // At least 1 page must be mapped for it to work
-    kheap_map_page();
+    size_t heap_pages = ALIGN_UP(KHEAP_SIZE, PAGE_SIZE) / PAGE_SIZE;
+    DEBUG("Mapping %d kernel heap pages at 0x%p", heap_pages, kheap_start);
+
+    uintptr_t current_addr = kheap_start;
+
+    // Map/alloc enough pages for heap (KHEAP_SIZE)
+    for (size_t i=0; i<heap_pages; i++)
+    {
+        uintptr_t phys = pmm_alloc();
+        if (phys == 0)
+        {
+            panic(NULL, "Not enough memory available to initialize kernel heap.");
+        }
+
+        paging_map_page(kernel_pml4, current_addr, phys, PTE_PRESENT | PTE_WRITABLE);
+        current_addr += PAGE_SIZE;
+    }
+
+    end = current_addr;
 
     // Give linked list head its properties
     head = (struct heap_block_t*)kheap_start;
-    head->size = PAGE_SIZE - sizeof(struct heap_block_t);
+    head->size = (end-kheap_start) - sizeof(struct heap_block_t);
     head->free = true;
     head->next = NULL;
-    DEBUG("kheap initialized, head=0x%p, size=%u", head, head->size);
+    DEBUG("Kernel heap initialized, head=0x%p, size=%u bytes", head, head->size);
 }
 
 void* kmalloc(size_t size)
@@ -73,12 +69,12 @@ void* kmalloc(size_t size)
         if (curr->free && curr->size >= size)
         {
             // We split the block if it is big enough
-            if (curr->size >= size + BLOCK_MIN_SIZE)
+            if (curr->size >= size + sizeof(struct heap_block_t) + 16)
             {
                 //struct heap_block_t* new_block = (struct heap_block_t*)((uintptr_t)curr + sizeof(struct heap_block_t) + size);
-                struct heap_block_t* split = (struct heap_block_t*)((uintptr_t)curr + sizeof(*curr) + size);
+                struct heap_block_t* split = (struct heap_block_t*)((uintptr_t)curr + sizeof(struct heap_block_t) + size);
                 
-                split->size = curr->size - size - sizeof(*curr);
+                split->size = curr->size - size - sizeof(struct heap_block_t);
                 split->free = true;
                 split->next = curr->next;
 
@@ -94,25 +90,12 @@ void* kmalloc(size_t size)
         curr = curr->next;
     }
 
-    // If we're here it means we didn't have enough memory
-    // for the block allocation. So we will allocate more..
-    uintptr_t old_end = end;
-    kheap_grow(size + sizeof(struct heap_block_t));
-
-    struct heap_block_t* block = (struct heap_block_t*)old_end;
-    block->size = ALIGN_UP(end - old_end - sizeof(struct heap_block_t), 16);
-    block->free = true;
-    block->next = NULL;
-
-    // Put the block at the end of the list
-    curr = head;
-    while (curr->next)
-    {
-        curr = curr->next;
-    }
-    curr->next = block;
-
-    return kmalloc(size);
+    // No growing. If we're here it means the initial pool
+    // wasn't sufficient. Too bad.
+    DEBUG("Kernel heap is OUT OF MEMORY!");
+    // if we were terrorists maybe we should panic
+    // or just wait for others to free stuff?
+    return NULL;
 }
 
 void kfree(void* ptr)
@@ -142,6 +125,6 @@ void kfree(void* ptr)
 // Should return a pointer to top of the stack (as stack grows DOWNWARDS)
 void* kalloc_stack()
 {
-    uint8_t* ptr = kmalloc(PROCESS_STACK_SIZE);
+    uint8_t* ptr = kmalloc(PROCESS_STACK_SIZE); // As it's out of kmalloc, stack is already mapped into kernel space
     return ptr ? ptr+PROCESS_STACK_SIZE : NULL;
 }

src/mem/heap/kheap.h

@@ -14,13 +14,15 @@
 
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 
 struct heap_block_t
 {
     size_t size;
-    bool free;
+    bool free; // 1byte
+    uint8_t reserved[7]; // (7+1 = 8 bytes)
     struct heap_block_t* next;
-};
+} __attribute__((aligned(16)));
 
 void kheap_init();
 void* kmalloc(size_t size);

src/mem/misc/utils.c

@@ -77,52 +77,3 @@ int memcmp(const void* s1, const void* s2, size_t n)
 
 	return 0;
 }
-
-// Display the memmap so we see how the memory is laid out at handoff
-void memmap_display(struct limine_memmap_response* response)
-{
-	DEBUG("Got memory map from Limine: revision %u, %u entries", response->revision, response->entry_count);
-
-	for (size_t i=0; i<response->entry_count; i++)
-	{
-		struct limine_memmap_entry* entry = response->entries[i];
-		char type[32] = {0};
-		switch(entry->type)
-		{
-			case LIMINE_MEMMAP_USABLE:
-				strcpy(type, "USABLE");
-				break;
-			case LIMINE_MEMMAP_RESERVED:
-				strcpy(type, "RESERVED");
-				break;
-			case LIMINE_MEMMAP_ACPI_RECLAIMABLE:
-				strcpy(type, "ACPI_RECLAIMABLE");
-				break;
-			case LIMINE_MEMMAP_ACPI_NVS:
-				strcpy(type, "ACPI_NVS");
-				break;
-			case LIMINE_MEMMAP_BAD_MEMORY:
-				strcpy(type, "BAD_MEMORY");
-				break;
-			case LIMINE_MEMMAP_BOOTLOADER_RECLAIMABLE:
-				strcpy(type, "BOOTLOADER_RECLAIMABLE");
-				break;
-			case LIMINE_MEMMAP_KERNEL_AND_MODULES:
-				strcpy(type, "KERNEL_AND_MODULES");
-				break;
-			case LIMINE_MEMMAP_FRAMEBUFFER:
-				strcpy(type, "FRAMEBUFFER");
-				break;
-			default:
-				strcpy(type, "UNKNOWN");
-				break;
-		}
-		DEBUG("entry %02u: [0x%016x | %016u bytes] - %s", i, entry->base, entry->length, type);
-	}
-}
-
-// Display the HHDM
-void hhdm_display(struct limine_hhdm_response* hhdm)
-{
-	DEBUG("Got HHDM revision=%u offset=0x%p", hhdm->revision, hhdm->offset);
-}

src/mem/paging/paging.c

@@ -24,7 +24,7 @@ If we use 1GB huge pages: PML4 -> PDPT -> 1gb pages
 4KB (regular size): PML4 -> PDPT -> PD -> PT -> 4kb pages
 */
 
-static inline void load_cr3(uint64_t value) {
+void load_cr3(uint64_t value) {
     asm volatile ("mov %0, %%cr3" :: "r"(value) : "memory");
 }
 
@@ -187,6 +187,14 @@ void paging_init()
     }
     DEBUG("Mapped %u pages for framebuffer", page_count);
 
+    // test for flanterm
+    // When 10 pages are mapped, SOMETIMES (1 out of 50 times) it prints everything without problem!
+    // Other times it prints garbage (almost full cursors) and/or panics.
+/*     for (uint64_t i=0; i<10; i++)
+    {
+        paging_map_page(kernel_pml4, 0, kernel_phys_base+KERNEL_SIZE+i*PAGE_SIZE, PTE_WRITABLE);
+    } */
+
     // Finally, we load the physical address of our PML4 (root table) into cr3
     load_cr3(VIRT_TO_PHYS(kernel_pml4));
     DEBUG("cr3 loaded, we're still alive");

src/mem/paging/paging.h

@@ -16,6 +16,9 @@
 void paging_init();
 void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_t flags);
 
+// To swap root page tables
+void load_cr3(uint64_t value);
+
 extern uint64_t hhdm_off;
 
 #define PHYS_TO_VIRT(x) ((void*)((uintptr_t)(x) + hhdm_off))

src/mem/paging/pmm.c

@@ -66,7 +66,10 @@ static uintptr_t g_freelist = 0;
 
 uintptr_t pmm_alloc()
 {
-    if (!g_freelist) return 0;
+    if (!g_freelist)
+	{
+		panic(NULL, "PMM is out of memory!");		
+	}
     uintptr_t addr = g_freelist;
     g_freelist = *(uintptr_t*) PHYS_TO_VIRT(g_freelist);
     return addr;

src/mem/paging/vmm.c

@@ -68,5 +68,6 @@ void vmm_setup_pt_root()
 
 void vmm_init()
 {
-    vmm_setup_pt_root();
+    // NO U
+    //vmm_setup_pt_root();
 }

src/sched/process.c

@@ -11,10 +11,16 @@
 #include "string/string.h"
 #include "mem/gdt/gdt.h"
 #include "config.h"
+#include "io/serial/serial.h"
+
+#include "io/term/flanterm.h"
+extern struct flanterm_context* ft_ctx;
 
 struct process_t* processes_list;
 struct process_t* current_process;
 
+extern uint64_t *kernel_pml4;
+
 size_t next_free_pid = 0;
 
 void process_init()
@@ -52,15 +58,23 @@ struct process_t* process_create(char* name, void(*function)(void*), void* arg)
     proc->pid = next_free_pid++;
     proc->status = READY;
 
+    uint64_t* stack_top = (uint64_t*)kalloc_stack();
+    // push return address to the stack so when "ret" hits we jmp to exit instead of idk what
+    // stack grows DOWNWARDS!!
+    *(--stack_top) = (uint64_t)process_exit;
+
     proc->context = ctx;
     proc->context->iret_ss = KERNEL_DATA_SEGMENT; // process will live in kernel mode
-    proc->context->iret_rsp = (uint64_t)kalloc_stack();
+    proc->context->iret_rsp = (uint64_t)stack_top;
     proc->context->iret_flags = 0x202; //bit 2 and 9 set (Interrupt Flag)
     proc->context->iret_cs = KERNEL_CODE_SEGMENT;
     proc->context->iret_rip = (uint64_t)function; // beginning of executable code
     proc->context->rdi = (uint64_t)arg; // 1st arg is in rdi (as per x64 calling convention)
     proc->context->rbp = 0; 
 
+    // Kernel PML4 as it already maps code/stack (when switching to userland we'll have to change that)
+    proc->root_page_table = kernel_pml4;
+
     proc->next = 0;
 
     process_add(&processes_list, proc);
@@ -127,3 +141,22 @@ struct process_t* process_get_next(struct process_t* process)
     if (!process) return NULL;
     return process->next;
 }
+
+// Will be used to clean up resources (if any, when we implement it)
+// Just mark as DEAD then idle. Scheduler will delete process at next timer interrupt % quantum.
+void process_exit()
+{
+    DEBUG("Exiting from process '%s'", current_process->name);
+    CLEAR_INTERRUPTS;
+    if (current_process)
+    {
+        current_process->status = DEAD;
+    }
+    SET_INTERRUPTS;
+    
+    //outb(0x20, 0x20);
+    for (;;)
+    {
+        asm("hlt");
+    }
+}

src/sched/process.h

@@ -9,6 +9,7 @@
 
 #include <stddef.h>
 #include "config.h"
+#include <stdint.h>
 
 typedef enum 
 {
@@ -24,6 +25,7 @@ struct process_t
 
     status_t status;
     struct cpu_status_t* context;
+	void* root_page_table; // Process PML4 (should contain kernel PML4 in higher half [256-511]
     struct process_t* next;
 };
 
@@ -32,6 +34,7 @@ struct process_t* process_create(char* name, void(*function)(void*), void* arg);
 void process_add(struct process_t** processes_list, struct process_t* process);
 void process_delete(struct process_t** processes_list, struct process_t* process);
 struct process_t* process_get_next(struct process_t* process);
+void process_exit();
 
 void process_display_list(struct process_t* processes_list);
 

src/sched/scheduler.c

@@ -6,9 +6,13 @@
 
 #include "kernel.h"
 #include "process.h"
+#include "mem/paging/paging.h"
+#include <stdint.h>
+#include "io/serial/serial.h"
 
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
+extern struct process_t* idle_proc;
 
 void scheduler_init()
 {
@@ -18,8 +22,19 @@ void scheduler_init()
 
 struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
 {
+    if (context == NULL)
+    {
+        panic(NULL, "Scheduler called with NULL context"); 
+    }
+
+    if (current_process == NULL)
+    {
+        // If no more processes, then set IDLE as the current process, that's it.
+        current_process = idle_proc;
+    }
+
     current_process->context = context;
-    current_process->status = READY;
+    //current_process->status = READY;
 
     for (;;) {
         struct process_t* prev_process = current_process;
@@ -34,6 +49,8 @@ struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
         if (current_process != NULL && current_process->status == DEAD)
         {
             process_delete(&prev_process, current_process);
+            current_process = NULL;
+            return idle_proc->context;
         } else
         {
             current_process->status = RUNNING;
@@ -41,6 +58,10 @@ struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
         }
     }
 
-    DEBUG("current_process={pid=%u name='%s'}", current_process->pid, current_process->name);
+    DEBUG("current_process={pid=%u, name='%s', root_page_table[virt]=%p}", current_process->pid, current_process->name, current_process->root_page_table);
+
+    load_cr3(VIRT_TO_PHYS((uint64_t)current_process->root_page_table));
+    DEBUG("loaded process pml4 into cr3");
+
     return current_process->context;
 }

src/sched/scheduler.h

@@ -7,7 +7,7 @@
 #ifndef SCHEDULER_H
 #define SCHEDULER_H
 
-void scheduler_schedule();
+struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context);
 void scheduler_init();
 
 #endif

src/time/timer.c

@@ -18,6 +18,8 @@ interested in multi-core functionnality like SMP)
 
 volatile uint64_t ticks = 0;
 
+extern struct init_status init;
+
 void pic_remap()
 {
     uint8_t master_mask = inb(0x21);
@@ -91,4 +93,5 @@ void timer_init()
     pic_enable();
     pit_init();
     DEBUG("PIT initialized");
+    init.timer = true;
 }

symbols.py

@@ -0,0 +1,33 @@
+# Make assembly file from ELF symbols map
+# Then link it to kernel so it's aware of symbol names
+# then we can use that for the stack trace.
+
+print("Extracting symbols from map file to assembly...")
+
+with open("symbols.map", "r") as f:
+    lines = f.readlines()
+
+    symbols = []
+    for line in lines:
+        parts = line.split()
+        # output is formed like "address name"
+        symbols.append((parts[0], parts[1]))
+
+with open("symbols.S", "w") as f:
+    f.write("section .rodata\n")
+    f.write("global symbol_table\n")
+    f.write("global symbol_count\n")
+    f.write("symbol_table:\n")
+
+    for i, (addr, name) in enumerate(symbols):
+        f.write(f"    dq 0x{addr}\n")
+        f.write(f"    dq sym_name_{i}\n")
+
+    f.write("\nsymbol_count: dq " + str(len(symbols)) + "\n\n")
+
+    for i, (addr, name) in enumerate(symbols):
+        # escaping quotes
+        safe_name = name.replace('"', '\\"')
+        f.write(f'sym_name_{i}: db "{safe_name}", 0\n')
+
+print("Done!")