feat(core): v0.5.1 - process isolation and syscalls

- Implemented CR3 switching in scheduler for process isolation

- Added 'process' structure and PML4 cloning (vmm_create_address_space)

- Added NASM crt0 and C entry point for userspace apps

.gitignore

@@ -1,4 +1,5 @@
 .cache
 build*
 .venv
-initrd/image.cpio
+initrd/image.cpio
+initramfs/*

CMakeLists.txt

@@ -6,15 +6,30 @@ set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
 
-add_subdirectory(bootloader)
-add_subdirectory(kernel)
-
 find_program(MCOPY_EXE mcopy)
 find_program(MKFS_EXE mkfs.fat)
 find_program(CPIO_EXE cpio)
 find_program(QEMU_EXE qemu-system-x86_64)
 set(OVMF_PATH "/usr/share/edk2/ovmf/OVMF_CODE.fd" CACHE FILEPATH "Path to OVMF bios")
 
+execute_process(
+    COMMAND git describe --tags --always --dirty
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE KERNEL_VERSION
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+if(NOT KERNEL_VERSION)
+    set(KERNEL_VERSION "unknown-version")
+endif()
+
+message(STATUS "Building termOS version: ${KERNEL_VERSION}")
+add_compile_definitions(TERMOS_VERSION=\"${KERNEL_VERSION}\")
+
+add_subdirectory(bootloader)
+add_subdirectory(kernel)
+add_subdirectory(userspace)
+
 if(MCOPY_EXE AND MKFS_EXE AND CPIO_EXE)
     set(IMG_FILE "${CMAKE_BINARY_DIR}/termOS.img")
     
@@ -27,7 +42,7 @@ if(MCOPY_EXE AND MKFS_EXE AND CPIO_EXE)
         COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_BINARY_DIR}
         COMMAND sh -c "find . -mindepth 1 ! -name '*.cpio' -print0 | ${CPIO_EXE} --null -ov -H newc > \"${INITRAMFS_CPIO_FILE}\""
         WORKING_DIRECTORY ${INITRAMFS_SRC_DIR}
-        DEPENDS ${INIT_FILES}
+        DEPENDS ${INIT_FILES} init
         VERBATIM
         COMMENT "Packing initramfs to cpio..."
     )

bootloader/CMakeLists.txt

@@ -4,6 +4,7 @@ set(UEFI_COMPILE_OPTIONS
     -std=c23
     -target x86_64-unknown-windows-msvc
     -Wall -Wextra
+    -fno-builtin
     $<$<CONFIG:Release>:-Werror>
 )
 

initramfs/test.txt

@@ -1 +0,0 @@
-Meow!!

initramfs/test1.txt

@@ -1 +0,0 @@
-Nyaaa

kernel/CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.20)
-project(termOS_krn LANGUAGES C ASM_NASM)
+project(dewar LANGUAGES C ASM_NASM)
 
 set(CMAKE_C_STANDARD 23)
 set(CMAKE_C_STANDARD_REQUIRED ON)
@@ -9,7 +9,7 @@ if (NOT DEFINED ARCH)
     set(ARCH "x86_64")
 endif()
 
-message(STATUS "TermOS Kernel: Building for architecture '${ARCH}'")
+message(STATUS "Dewar kernel: Building for architecture '${ARCH}'")
 
 
 file(GLOB_RECURSE KERNEL_SOURCES CMAKE_CONFIGURE_DEPENDS

kernel/inc/arch/x86_64/cpuinfo.h

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+#pragma once
+#include <types.h>
+
+#define CPU_FEAT_FPU      (1ULL << 0)
+#define CPU_FEAT_TSC      (1ULL << 1)
+#define CPU_FEAT_MSR      (1ULL << 2)
+#define CPU_FEAT_APIC     (1ULL << 3)
+#define CPU_FEAT_MTRR     (1ULL << 4)
+#define CPU_FEAT_PAE      (1ULL << 5)
+
+#define CPU_FEAT_SSE      (1ULL << 10)
+#define CPU_FEAT_SSE2     (1ULL << 11)
+#define CPU_FEAT_SSE3     (1ULL << 12)
+#define CPU_FEAT_SSSE3    (1ULL << 13)
+#define CPU_FEAT_SSE4_1   (1ULL << 14)
+#define CPU_FEAT_SSE4_2   (1ULL << 15)
+
+#define CPU_FEAT_AVX      (1ULL << 20)
+#define CPU_FEAT_F16C     (1ULL << 21)
+#define CPU_FEAT_RDRAND   (1ULL << 22)
+
+#define CPU_FEAT_HYPERVISOR (1ULL << 30) 
+
+typedef struct {
+    u64 user_rsp;
+    u64 kernel_rsp;
+    u64 self;
+
+    u64 features;
+    char vendor[13];
+    u32 family;
+    u32 model;
+} cpu_info;
+
+extern cpu_info g_cpu;
+
+void cpuinfo_init(u64 kernel_stack_top);
+bool cpu_has(u64 feature);

kernel/inc/arch/x86_64/syscall.h

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#pragma once
+
+#define MSR_EFER         0xC0000080
+#define MSR_STAR         0xC0000081
+#define MSR_LSTAR        0xC0000082
+#define MSR_FMASK        0xC0000084
+#define MSR_KERNEL_GS_BASE 0xC0000102
+
+#define EFER_SCE         0x01 // System Call Enable
+
+typedef enum {
+    SYS_EXIT,
+    SYS_EXEC,
+    SYS_WRITE,
+} syscalls;
+
+void syscall_init();

kernel/inc/core/loader.h

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#pragma once
+
+#include <types.h>
+#include <core/scheduler.h>
+
+bool exec_init(process* p, const char* path);
+void init_task_entry();

kernel/inc/core/rand.h

@@ -4,4 +4,5 @@
 #pragma once
 #include <types.h>
 
-u64 shitrand();
+void rng_init();
+u64 krand();

kernel/inc/core/scheduler.h

@@ -3,15 +3,30 @@
 
 #pragma once
 #include <types.h>
+
+typedef enum process_state {
+    DEAD,
+    RUNNING,
+} process_state;
+
+typedef struct process {
+    u64 pid;
+    process_state state;
+    u64 pml4_phys;
+    struct process* parent;
+    char name[32];
+} process;
+
 typedef struct task {
     u64 rsp;
     struct task* next;
     u32 id;
     u32 sleep_ticks;
     u64 kernel_stack_top;
+    process* proc;
 } task;
 
 void sched_init();
-task* sched_spawn(void(*entry)());
+task* sched_spawn(void(*entry)(), process* owner);
 u64 sched_next(u64 curr_rsp);
 void yield(u64 ticks);

kernel/inc/core/userspace.h

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#pragma once
+
+void jump_to_userspace(void* entry, void* user_stack_top);

kernel/inc/drivers/shitgui.h

@@ -26,16 +26,8 @@ typedef struct {
     const unsigned char* base;
 } SG_Font;
 
-typedef struct {
-    SG_Context *ctx;
-    SG_Point pos;
-    const char *title;
-} SG_Window;
-
 void sg_init(SG_Context *ctx);
 u32 sg_get_pixel(SG_Context *ctx, SG_Point *p);
 void sg_put_img(SG_Context *ctx, SG_Point *p, SG_Image *img);
 void sg_draw_rect(SG_Context *ctx, SG_Point *p, u32 w, u32 h, u32 color);
-void sg_draw_char_bitmap(SG_Context *ctx, SG_Point *p, char c, u32 color, SG_Font *font);
-SG_Window* create_window(const char *title, SG_Point* size, SG_Point* position);
-void composer_task();
+void sg_draw_char_bitmap(SG_Context *ctx, SG_Point *p, char c, u32 color, SG_Font *font);

kernel/inc/mm/vmm.h

@@ -37,3 +37,6 @@
 
 void vmm_init(Bootinfo* info);
 u64* vmm_map_page(u64* pml4, u64 phys, u64 virt, u64 flags);
+u64 vmm_create_address_space();
+u64 vmm_get_current_cr3();
+void load_cr3(u64 pml4_addr);

kernel/inc/shell/builtins.h

@@ -10,4 +10,6 @@ void cmd_regs();
 void print_regs();
 void cmd_sleep();
 void cmd_debug();
-int rectest(int a);
+void cmd_rand();
+void cmd_ver();
+void cmd_userspace();

kernel/src/arch/x86_64/cpuinfo.c

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#include "types.h"
+#include <cpuinfo.h>
+
+#define MSR_GS_BASE         0xC0000101
+#define MSR_KERNEL_GS_BASE  0xC0000102
+
+cpu_info g_cpu = {0};
+
+static inline void cpuid(u32 leaf, u32 subleaf, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx) {
+    __asm__ volatile("cpuid"
+        : "=a"(*eax), "=b"(*ebx), "=c"(*ecx), "=d"(*edx)
+        : "a"(leaf), "c"(subleaf)
+    );
+}
+
+static inline void wrmsr(u32 msr, u64 val) {
+    u32 low = (u32)val;
+    u32 high = (u32)(val >> 32);
+    __asm__ volatile("wrmsr" :: "a"(low), "d"(high), "c"(msr));
+}
+
+void cpuinfo_init(u64 kernel_stack_top) {
+    g_cpu.kernel_rsp = kernel_stack_top;
+    g_cpu.self = (u64)&g_cpu;
+    wrmsr(MSR_KERNEL_GS_BASE, (u64)&g_cpu);
+
+
+    u32 eax, ebx, ecx, edx;
+
+    cpuid(0, 0, &eax, &ebx, &ecx, &edx);
+    
+    u32* vendor_ptr = (u32*)g_cpu.vendor;
+    vendor_ptr[0] = ebx;
+    vendor_ptr[1] = edx;
+    vendor_ptr[2] = ecx;
+    g_cpu.vendor[12] = '\0';
+
+    cpuid(1, 0, &eax, &ebx, &ecx, &edx);
+
+    g_cpu.family = (eax >> 8) & 0xF;
+    g_cpu.model  = (eax >> 4) & 0xF;
+    if (g_cpu.family == 6 || g_cpu.family == 15) {
+        g_cpu.model += ((eax >> 16) & 0xF) << 4;
+    }
+
+    if (edx & (1 << 0))  g_cpu.features |= CPU_FEAT_FPU;
+    if (edx & (1 << 4))  g_cpu.features |= CPU_FEAT_TSC;
+    if (edx & (1 << 5))  g_cpu.features |= CPU_FEAT_MSR;
+    if (edx & (1 << 6))  g_cpu.features |= CPU_FEAT_PAE;
+    if (edx & (1 << 9))  g_cpu.features |= CPU_FEAT_APIC;
+    if (edx & (1 << 12)) g_cpu.features |= CPU_FEAT_MTRR;
+    if (edx & (1 << 25)) g_cpu.features |= CPU_FEAT_SSE;
+    if (edx & (1 << 26)) g_cpu.features |= CPU_FEAT_SSE2;
+
+    if (ecx & (1 << 0))  g_cpu.features |= CPU_FEAT_SSE3;
+    if (ecx & (1 << 9))  g_cpu.features |= CPU_FEAT_SSSE3;
+    if (ecx & (1 << 19)) g_cpu.features |= CPU_FEAT_SSE4_1;
+    if (ecx & (1 << 20)) g_cpu.features |= CPU_FEAT_SSE4_2;
+    if (ecx & (1 << 28)) g_cpu.features |= CPU_FEAT_AVX;
+    if (ecx & (1 << 29)) g_cpu.features |= CPU_FEAT_F16C;
+    
+    if (ecx & (1 << 30)) g_cpu.features |= CPU_FEAT_RDRAND;
+    
+    if (ecx & (1 << 31)) g_cpu.features |= CPU_FEAT_HYPERVISOR;
+}
+
+bool cpu_has(u64 feature) {
+    return (g_cpu.features & feature) != 0;
+}

kernel/src/arch/x86_64/entry.asm

@@ -27,9 +27,10 @@ stack_guard:
 global stack_bottom
 stack_bottom:
     resb 16384
+global stack_top
 stack_top:
 
-section .text
+section .text.entry
 global _start
 global gdt_flush
 extern kmain

kernel/src/arch/x86_64/syscall.asm

@@ -0,0 +1,70 @@
+; SPDX-License-Identifier: GPL-3.0-or-later
+; Copyright (c) 2026 0xKarinyash
+
+bits 64
+
+extern syscall_dispatch
+global syscall_entry
+
+section .text
+
+syscall_entry:
+    swapgs
+    mov [gs:0], rsp ; saving users rsp in g_cpu.user_rsp
+    mov rsp, [gs:8] ; load kernel rsp from g_cpu.kernel_rsp
+
+    push qword [gs:0]
+    push r11 ; rflags
+    push rcx ; rip
+
+    push rbp
+    push rbx
+    push rdi
+    push rsi
+    push rdx
+    push r10
+    push r8
+    push r9
+    push r12
+    push r13
+    push r14
+    push r15
+
+    ; preparing c code
+    ; c waits rdi, rsi, rdx, rcx, r8, r9
+    ; user sent rax, rdi, rsi, rdx, r10, r8 (rax=id)
+
+    mov r9,  r8             ; 6th arg
+    mov r8,  r10            ; 5th arg
+    mov rcx, rdx            ; 4th arg
+    mov rdx, rsi            ; 3rd arg
+    mov rsi, rdi            ; 2nd arg
+    mov rdi, rax            ; 1st arg (id)
+
+    call syscall_dispatch
+
+    ; restoring context except RAX (result there)
+    pop r15
+    pop r14
+    pop r13
+    pop r12
+    pop r9
+    pop r8
+    pop r10
+    pop rdx
+    pop rsi
+    pop rdi
+    pop rbx
+    pop rbp
+    pop rcx ; rip
+    pop r11 ; rflags
+    add rsp, 8 ; skip rsp
+
+    mov [gs:8], rsp
+    mov rsp, [gs:0]
+    swapgs
+
+    o64 sysret
+
+
+    

kernel/src/arch/x86_64/syscall.c

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#include <cpuinfo.h>
+#include <syscall.h>
+#include <types.h>
+#include <drivers/console.h>
+#include <mm/pmm.h>
+#include <mm/vmm.h>
+
+static inline void wrmsr(u32 msr, u64 val) {
+    u32 low = (u32)val;
+    u32 high = (u32)(val >> 32);
+    __asm__ volatile("wrmsr" :: "a"(low), "d"(high), "c"(msr));
+}
+
+static inline u64 rdmsr(u32 msr) {
+    u32 low, high;
+    __asm__ volatile("rdmsr" : "=a"(low), "=d"(high) : "c"(msr));
+    return ((u64)high << 32) | low;
+}
+
+extern void syscall_entry();
+
+void syscall_init() {
+    u64 efer = rdmsr(MSR_EFER);
+    wrmsr(MSR_EFER, efer | 1); // Enabling SCE in EFER. Just enabling 0 bit
+
+    // setting up STAR
+    // 32:47 kernel selector (0x08)
+    // 48:64 user selector (0x01 cuz sysret adds +16 for CS and +8 for SS)
+    u64 star = (0x13ULL << 48) | (0x08ULL << 32); 
+    wrmsr(MSR_STAR, star);
+
+    wrmsr(MSR_LSTAR, (u64)syscall_entry); // setting handler adress
+
+    // masking flags (IA32_FMASK)
+    // 9 bit for finterrupts in syscall (IF) and few more necessary flags
+    wrmsr(MSR_FMASK, 0x200); // masking only IF
+
+    if (g_cpu.kernel_rsp == 0) {
+        void* stack_phys = pmm_alloc_page();
+        g_cpu.kernel_rsp = (u64)stack_phys + HHDM_OFFSET + 4096;
+    }
+
+    wrmsr(MSR_KERNEL_GS_BASE, (u64)&g_cpu);
+}
+
+u64 syscall_dispatch(u64 id, u64 arg1, u64 arg2, u64 arg3, u64 arg4, u64 arg5) {
+    switch (id) {
+        case SYS_EXIT: {
+            kprintf("\n[Dewar] process exited with code %d", arg1);
+            while(1) __asm__ ("hlt"); // stub
+            return 0;
+        }
+        case SYS_EXEC: {
+            kprintf("\n[Dewar] process called exec syscall");
+            return 0; // stub as well
+        }
+        case SYS_WRITE: {
+            kprintf("%s", (char*)arg1);
+            return 0;
+        }
+        default: kprintf("[Dewar] Unknown syscall %d\n", id); return -1;
+    }
+}

kernel/src/core/loader.c

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#include <core/loader.h>
+#include <core/userspace.h>
+#include <core/scheduler.h>
+#include <core/string.h>
+
+#include <shell/ksh.h>
+
+#include <mm/pmm.h>
+#include <mm/vmm.h>
+#include <mm/heap.h>
+#include <mm/memory.h>
+
+#include <fs/vfs.h>
+
+#include <drivers/console.h>
+#include <types.h>
+
+extern task* curr_task;
+
+bool exec_init(process* p, const char* path) {
+    kprintf("[Loader] loading %s...\n", path);
+    fs_node* file = vfs_open(path);
+    if (!file) {
+        kprintf("[Loader] Error: %s not found in initramfs!\n", path);
+        return false;
+    }
+
+    u64 virt_code = 0x400000;
+    u64 virt_stack = 0x800000;
+    u64 stack_size = 8192;     
+
+    u64 bytes_left = file->len;
+    u64 offset = 0;
+    u64 page_idx = 0;
+
+    while (bytes_left > 0) {
+        void* phys = pmm_alloc_page();
+        if (!phys) {
+            kprintf("Loader: OOM!\n");
+            return false;
+        }
+
+        vmm_map_page((u64*)p->pml4_phys, (u64)phys, virt_code + (page_idx * 4096), PTE_PRESENT | PTE_RW | PTE_USER);
+
+        void* k_ptr = (void*)(HHDM_OFFSET + (u64)phys);
+        memset(k_ptr, 0, 4096);
+        
+        u64 chunk = (bytes_left > 4096) ? 4096 : bytes_left;
+        vfs_read(file, offset, chunk, (u8*)k_ptr);
+
+        bytes_left -= chunk;
+        offset += chunk;
+        page_idx++;
+    }
+
+    for (u64 i = 0; i < (stack_size / 4096); i++) {
+        void* phys = pmm_alloc_page();
+        vmm_map_page((u64*)p->pml4_phys, (u64)phys, virt_stack + (i * 4096), PTE_PRESENT | PTE_RW | PTE_USER);
+        memset((void*)(HHDM_OFFSET + (u64)phys), 0, 4096);
+    }
+
+    load_cr3(p->pml4_phys);
+
+    // __asm__ volatile(
+    //     "mov %%cr3, %%rax\n\t"
+    //     "mov %%rax, %%cr3\n\t"
+    //     ::: "rax", "memory"
+    // );
+
+    kprintf("[Loader] Transferring control to userspace...\n");
+    jump_to_userspace((void*)virt_code, (void*)(virt_stack + stack_size));
+    
+    return true; // unreachable
+}
+
+void init_task_entry() {
+    process* init_proc = (process*)malloc(sizeof(process));
+    init_proc->pid = 1;
+    init_proc->state = RUNNING;
+    init_proc->pml4_phys = vmm_create_address_space();
+    strcpy(init_proc->name, "init");
+
+    curr_task->proc = init_proc;
+    
+    if (!exec_init(init_proc, "/init")) {
+        kprintf("FATAL: Could not load /init\n");
+        sched_spawn(ksh, nullptr); 
+        
+        while(1) __asm__("hlt"); 
+    }
+}

kernel/src/core/panic.c

@@ -51,7 +51,9 @@ const char* fun_messages[] = {
     "Attaboy, Jack. He's good. Really good.",
     "Zhenih priehal",
     "YOUR PC WAS BLOCKED BY FBI FOR WATCHING PORNOGRAPHY SEND 20 US DOLLARS",
-    "fuck off"
+    "fuck off",
+    "Your GPU is now mining Ethereum for me. Thanks.",
+    "Your PC is locked!\n\t\t\t\tPay a fee of 0.019082006 bitcoins to a wallet 1KtoProchitalTotSosal to get decryption key!",
 };
 
 
@@ -102,7 +104,7 @@ void draw_panic_bg() {
     console_set_default_color(0xFFFFFF);
     
     u64 msg_count = sizeof(fun_messages) / sizeof(fun_messages[0]);
-    u8 rand_num = shitrand() % msg_count;
+    u8 rand_num = krand() % msg_count;
 
     kprintf("\n\n");
     kprintf("\t\t\t\t^bKERNEL PANIC^!  :( \n");

kernel/src/core/rand.c

@@ -1,15 +1,45 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 // Copyright (c) 2025 0xKarinyash
 
+#include "bootinfo.h"
 #include <core/rand.h>
+#include <cpuinfo.h>
 #include <types.h>
 
-// really shiity rand lol. 
-// not shitty.. basic.
+static u64 prng_state = 0;
 
-u64 shitrand() {
-    int lo, hi;
+static inline u64 rdtsc() {
+    u32 lo, hi;
     __asm__ volatile ("rdtsc" : "=a" (lo), "=d" (hi));
 
     return ((u64)hi << 32) | lo;
+}
+
+void rng_init() {
+    prng_state = rdtsc();
+    if (prng_state == 0) prng_state = BOOTINFO_MAGIC; // why not reuse "termOS"?
+}
+
+static u64 xorshift_rand() {
+    u64 x = prng_state;
+    x ^= x << 13;
+    x ^= x >> 7;
+    x ^= x << 17;
+    return prng_state = x;
+}
+
+static bool hw_rand(u64 *val) {
+    u8 ok;
+    __asm__ volatile ("rdrand %0; setc %1" 
+                    : "=r" (*val), "=qm" (ok));
+    return ok != 0;
+}
+
+u64 krand() {
+    u64 res;
+    if (cpu_has(CPU_FEAT_RDRAND)) {
+        if (hw_rand(&res)) return res;
+    }
+
+    return xorshift_rand();
 }

kernel/src/core/scheduler.c

@@ -3,28 +3,41 @@
 
 #include <core/panic.h>
 #include <core/scheduler.h>
+#include <core/string.h>
 #include <mm/heap.h>
+#include <mm/vmm.h>
+#include <cpuinfo.h>
 #include <gdt.h>
 
 task* curr_task = nullptr;
 u32 next_pid = 1;
 
+
 extern void irq0_handler();
+extern u64 pml4_kernel_phys;
+
+static process kernel_process;
 
 void sched_init() {
-    task* kt = (task*)malloc(sizeof(task));
+    kernel_process.pid = 0;
+    kernel_process.state = RUNNING;
+    kernel_process.pml4_phys = pml4_kernel_phys;
+    strcpy(kernel_process.name, "kernel");
 
+    task* kt = (task*)malloc(sizeof(task));
     kt->id = 0;
+    kt->proc = &kernel_process;
     kt->sleep_ticks = 0;
     kt->next = kt;
 
     curr_task = kt;
 }
 
-task* sched_spawn(void(*entry)()) {
+task* sched_spawn(void(*entry)(), process* owner) {
     task* t = (task*)malloc(sizeof(task));
     if (!t) return nullptr;
-    
+    if (!owner) owner = &kernel_process;
+
     u64 stack_size = 16384;
     u8* stack_base = (u8*)malloc(stack_size);
     if (!stack_base) panic("OOM for task stack");
@@ -42,6 +55,7 @@ task* sched_spawn(void(*entry)()) {
     for (u8 i = 0; i < 15; i++) *--rsp = 0; // R15 .. RAX
 
     t->rsp = (u64)rsp;
+    t->proc = owner;
     t->id = next_pid++;
     t->sleep_ticks = 0;
     t->next = curr_task->next;
@@ -66,8 +80,11 @@ u64 sched_next(u64 curr_rsp) {
     task* next = curr_task->next;
     while (next != curr_task && next->sleep_ticks > 0) next = next->next; // what the fuck i just wrote  
 
+    if (next->proc->pml4_phys != curr_task->proc->pml4_phys) load_cr3(next->proc->pml4_phys);
+
     curr_task = next;
     tss.rsp0 = curr_task->kernel_stack_top;
+    g_cpu.kernel_rsp = curr_task->kernel_stack_top;
     return curr_task->rsp;
 }
 

kernel/src/core/userspace.c

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKarinyash
+
+#include <core/userspace.h>
+#include <types.h>
+
+#define USER_DS (0x18 | 3)
+#define USER_CS (0x20 | 3)
+#define RFLAGS_IF 0x202
+
+void jump_to_userspace(void* entry, void* user_stack_top) {
+    __asm__ volatile (
+        "mov %0, %%ds\n"
+        "mov %0, %%es\n"
+        "mov %0, %%fs\n"
+        :: "r" ((u64)USER_DS) : "memory"
+    );
+
+    __asm__ volatile (
+        "pushq %0\n" // SS (User Data Selector)
+        "pushq %1\n" // RSP (User Stack Pointer)
+        "pushq %2\n" // RFLAGS
+        "pushq %3\n" // CS (User Code Selector)
+        "pushq %4\n" // RIP (Entry Point)
+        "iretq\n"
+        : 
+        : "r" ((u64)USER_DS),
+          "r" ((u64)user_stack_top),
+          "r" ((u64)RFLAGS_IF),
+          "r" ((u64)USER_CS),
+          "r" ((u64)entry)
+        : "memory"
+    );
+}

kernel/src/drivers/shitgui.c

@@ -8,11 +8,8 @@
 #include <mm/memory.h>
 
 #define SHITGUI_TRANSPARENCY_KEY 0xFF00FF
-#define SHITGUI_MAX_WINDOWS_AMOUNT 64
 
 SG_Context* main_context;
-SG_Window* windows[SHITGUI_MAX_WINDOWS_AMOUNT]; // нет блять линукс
-u64 windows_amount = 0;
 
 void sg_init(SG_Context *ctx) {
     main_context = ctx;
@@ -85,64 +82,4 @@ void sg_draw_char_bitmap(SG_Context *ctx, SG_Point *p, char c, u32 color, SG_Fon
             }
         }
     }
-}
-
-SG_Window* create_window(const char *title, SG_Point* size, SG_Point* position) {
-    if (windows_amount >= SHITGUI_MAX_WINDOWS_AMOUNT) return nullptr; 
-    SG_Context* ctx = nullptr;
-    u32* fb = nullptr;
-    SG_Window* window = nullptr;
-
-    ctx = (SG_Context*)malloc(sizeof(SG_Context));
-    if (!ctx) goto fail; // goto is GOOD for cleaning up in C stfu. 
-                         // Mainline linux kernel contains 100k gotos
-
-    fb = malloc(size->x * size->y * sizeof(u32));
-    if (!fb) goto fail;
-    memset(fb, 0, size->x * size->y * sizeof(u32));
-
-    window = (SG_Window*)malloc(sizeof(SG_Window));
-    if (!window) goto fail;
-
-    ctx->fb = fb;
-    ctx->height = size->y;
-    ctx->width = size->x;
-    ctx->pitch = size->x;
-    
-    
-    window->ctx = ctx;
-    window->title = title;
-    window->pos.x = position->x;
-    window->pos.y = position->y;
-
-    windows[windows_amount] = window;
-    windows_amount++;    
-
-    return window;
-
-fail:
-    if (ctx) free(ctx);
-    if (fb) free(fb);
-    if (window) free(window);
-
-    return nullptr;
-}
-
-void render_window(SG_Context *ctx, SG_Window *window) {
-    SG_Image img = {0};
-    img.buffer = window->ctx->fb;
-    if (!img.buffer) panic("No img buffer found");
-    img.height = window->ctx->height;
-    img.width  = window->ctx->width;
-
-    sg_put_img(ctx, &window->pos, &img);
-}
-
-void composer_task() {
-    while (true) {
-        for (u64 i = 0; i < windows_amount; i++) {
-            render_window(main_context, windows[i]);
-        }
-        yield(1);
-    }
 }

kernel/src/kmain.c

@@ -2,6 +2,7 @@
 // Copyright (c) 2025 0xKarinyash
 
 #include "bootinfo.h"
+
 #include <shell/ksh.h>
 
 #include <types.h>
@@ -14,10 +15,14 @@
 #include <core/panic.h>
 #include <core/scheduler.h>
 #include <core/splash.h>
+#include <core/rand.h>
+#include <core/loader.h>
 
 #include <gdt.h>
 #include <idt.h>
 #include <pic.h>
+#include <cpuinfo.h>
+#include <syscall.h>
 
 #include <mm/pmm.h>
 #include <mm/vmm.h>
@@ -30,6 +35,7 @@
 #define BG_COLOR 0x111111
 
 extern u64 _kernel_end;
+extern void* stack_top;
 static SG_Context sg_ctx;
 
 void kmain(Bootinfo* info) {
@@ -40,6 +46,10 @@ void kmain(Bootinfo* info) {
 
     if (info->magic != BOOTINFO_MAGIC) panic("Corrupt bootinfo!");
 
+    cpuinfo_init((u64)&stack_top);
+    kprintf("Got CPUINFO\n");
+    rng_init();
+    kprintf("RNG initialized\n");
     gdt_init();
     kprintf("GDT initialized\n");
     idt_init();
@@ -58,6 +68,7 @@ void kmain(Bootinfo* info) {
     kprintf("Scheduler initialized\n");
     sg_init(&sg_ctx);
     kprintf("Shitgui initialized\n");
+    syscall_init();
 
     info = (Bootinfo*)PHYS_TO_HHDM((u64)info);
 
@@ -79,9 +90,20 @@ void kmain(Bootinfo* info) {
 
     show_splash(&sg_ctx);
 
-    sched_spawn(composer_task);
-    sched_spawn(ksh);
-    if (!info->initramfs.addr) kprintf("^rWARNING^!: Failed to load ^yinitramfs^!, VFS is empty.\n\n");
+    bool staying_in_ksh = false;
+    if (!info->initramfs.addr) { 
+        kprintf("^rWARNING^!: Failed to load ^yinitramfs^!! Staying in kernel rescue shell!\n\n"); 
+        staying_in_ksh = true; 
+    }
+
+    kprintf("Press any key to stay in ^gksh^!. \nPress ^yenter^! to continue booting in ring 3\n");
+    char c = '\n';
+    c = console_getc();
+    if (c != '\n') staying_in_ksh = true;
+    
+    if (staying_in_ksh) sched_spawn(ksh, nullptr);
+    else sched_spawn(init_task_entry, nullptr);
+    
     __asm__ volatile("sti");
     
     while (true) __asm__ volatile("hlt");

kernel/src/mm/vmm.c

@@ -11,6 +11,7 @@
 #include "bootinfo.h"
 
 u64* pml4_kernel = nullptr;
+u64 pml4_kernel_phys = 0;
 static bool is_initialized = false;
 
 extern u64 _kernel_start; 
@@ -89,26 +90,30 @@ void vmm_unmap_page(u64* pml4, u64 virt) {
     u64 pdpt_idx = VMM_PDPT_INDEX(virt);
     u64 pml4_idx = VMM_PML4_INDEX(virt);
 
-    if (!(pml4[pml4_idx] & PTE_PRESENT)) return;
-    u64* pdpt = get_table_virt(PTE_GET_ADDR(pml4[pml4_idx]));
-    
-    if (!(pdpt[pdpt_idx] & PTE_PRESENT)) return;
-    u64* pd = get_table_virt(PTE_GET_ADDR(pdpt[pdpt_idx]));
-    
-    if (!(pd[pd_idx] & PTE_PRESENT)) return;
-    u64* pt = get_table_virt(PTE_GET_ADDR(pd[pd_idx]));
+    u64* pml4_virt = pml4;
+    if (is_initialized) pml4_virt = (u64*)PHYS_TO_HHDM((u64)pml4);
 
-    pt[pt_idx] = 0; 
+    if (!(pml4_virt[pml4_idx] & PTE_PRESENT)) return;
+    u64* pdpt_virt = get_table_virt(PTE_GET_ADDR(pml4_virt[pml4_idx]));
+    
+    if (!(pdpt_virt[pdpt_idx] & PTE_PRESENT)) return;
+    u64* pd_virt = get_table_virt(PTE_GET_ADDR(pdpt_virt[pdpt_idx]));
+    
+    if (!(pd_virt[pd_idx] & PTE_PRESENT)) return;
+    u64* pt_virt = get_table_virt(PTE_GET_ADDR(pd_virt[pd_idx]));
+
+    pt_virt[pt_idx] = 0; 
     
     __asm__ volatile("invlpg (%0)" :: "r" (virt) : "memory");
 }
 
-static inline void load_cr3(u64 pml4_addr) {
+void load_cr3(u64 pml4_addr) {
     __asm__ volatile ("mov %0, %%cr3" :: "r"(pml4_addr) : "memory");
 }
 
 void vmm_init(Bootinfo* info) {
-    pml4_kernel = pmm_alloc_page();
+    pml4_kernel_phys = (u64)pmm_alloc_page();
+    pml4_kernel = (u64*)pml4_kernel_phys;
     memset(pml4_kernel, 0, PAGE_SIZE);
 
     u64 k_virt_start = (u64)&_kernel_start; 
@@ -126,6 +131,28 @@ void vmm_init(Bootinfo* info) {
 
     bitmap = (u8*)PHYS_TO_HHDM((u64)bitmap);
     info->framebuffer.base = (u32*)FB_VIRT_BASE;
-    load_cr3((u64)pml4_kernel);
+    load_cr3(pml4_kernel_phys);
     is_initialized = true;
+}
+
+u64 vmm_create_address_space() {
+    u64 phys = (u64)pmm_alloc_page();
+    if (!phys) return 0;
+
+    u64* virt = (u64*)PHYS_TO_HHDM(phys);
+    memset(virt, 0, PAGE_SIZE);
+
+    u64* kernel_pml4_virt = get_table_virt((u64)pml4_kernel);
+
+    for (u32 i = 256; i < 512; i++) {
+        virt[i] = kernel_pml4_virt[i];
+    }
+
+    return phys;
+}
+
+u64 vmm_get_current_cr3() {
+    u64 cr3;
+    __asm__ volatile("mov %%cr3, %0" : "=r"(cr3));
+    return cr3;
 }

kernel/src/shell/builtins.c

@@ -1,14 +1,26 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 // Copyright (c) 2025 0xKarinyash
 
-#include <drivers/console.h>
-#include <core/rand.h>
 
-#include <drivers/timer.h>
 #include <types.h>
+#include <cpuinfo.h>
+
+#include <drivers/console.h>
+#include <drivers/timer.h>
+
+#include <core/rand.h>
+#include <core/loader.h>
+#include <core/scheduler.h>
+#include <core/string.h>
+
+#include <mm/vmm.h>
+#include <mm/heap.h>
+
+#include <shell/dbgcmd.h>
 
 #include "../data/cats.h"
-#include "shell/dbgcmd.h"
+
+extern task* curr_task;
 
 const char* ascii_logo[] = {
     "      /\\___/\\     ", 
@@ -21,47 +33,40 @@ const char* ascii_logo[] = {
     "     |_______|     " 
 };
 
-int rectest(int a) {
-    volatile int b = a + 1;
-    kprintf("%d", b);
-    return rectest(b * 2);
-}
-
 void cmd_kfetch() {
     u64 uptime_s = get_uptime() / 1000;
 
     kprintf("\n\n");
     kprintf("^p %s ^!\t\t^g kernel^!@^gtermos\n^0", ascii_logo[0]);
-    kprintf("^p %s ^!\t\t^!-------------\n^!", ascii_logo[1]);   
-    kprintf("^p %s ^!\t\t^gOS^!: termOS 0.0.1\n^!", ascii_logo[2]);   
-    kprintf("^p %s ^!\t\t^gKernel^!: sucks\n^!", ascii_logo[3]);   
+    kprintf("^p %s ^!\t\t^!-------------\n^!", ascii_logo[1]);
+    kprintf("^p %s ^!\t\t^gOS^!: termOS %s\n^!", ascii_logo[2], TERMOS_VERSION);   
+    kprintf("^p %s ^!\t\t^gKernel^!: Dewar (x86_64), build: %s %s\n^!", ascii_logo[3], __DATE__, __TIME__);   
     kprintf("^p %s ^!\t\t^gUptime^!: %d seconds\n^!", ascii_logo[4], uptime_s);   
     kprintf("^p %s ^!\t\t^gShell^!: ksh\n^!", ascii_logo[5]);   
-    kprintf("^p %s ^p\t\t^gDE^!: shitgui\n^!", ascii_logo[6]);   
-    kprintf("^p %s ^p\t\t^gCPU^!: %s\n^!", ascii_logo[7], "cool one");
+    kprintf("^p %s ^!\t\t^gDE^!: shitgui\n^!", ascii_logo[6]);   
+    kprintf("^p %s ^!\t\t^gCPU^!: %s (^yFamily^!: %d; ^yModel^!: %d)\n^!", ascii_logo[7], g_cpu.vendor, g_cpu.family, g_cpu.model);
     kprintf("\n\n");
 }
 
 void cmd_meow() {
     u64 cats_count = sizeof(cats) / sizeof(cats[0]);
-    u8 rand_num = shitrand() % cats_count;
+    u8 rand_num = krand() % cats_count;
     kprintf("Nyaaa!!\n\n%s\n\n", cats[rand_num]);
 }
 
 void cmd_help() {
     kprintf("Welcome to ^ptermOS^!'s ^gk^!ernel ^gsh^!ell!\n");
     kprintf("It loads when userspace is failed to load and acts as a basic rescue environment\n");
-    kprintf("At this moment i dont have userspace so it loads always\n");
     kprintf("Available commands:\n");
     
     kprintf("\t^rDebug^!:\n");
     kprintf("\t\t^ysleep^!       \t\tSleep for 3seconds\n");
     kprintf("\t\t^ydbg^!         \t\tTest new stuff\n");
     kprintf("\t\t^yregs^!        \t\tPrint current regs\n");
-    kprintf("\t\t^yrectest^!     \t\tTSS test\n");
     kprintf("\t\t^ypanic^!       \t\tPanics (lol)\n");
     kprintf("\t\t^yud2^!         \t\tPanics with #UD\n");
     kprintf("\t\t^ypf^!          \t\tPanics with #PF\n");
+    kprintf("\t\t^yuserspace^!   \t\tAttempt to jump in ring 3\n");
     
     kprintf("\t^pFun^!:\n");
     kprintf("\t\t^ysplash^!      \t\tShows splash (works kinda unstable)\n");
@@ -74,6 +79,8 @@ void cmd_help() {
     kprintf("\t^bMisc^!:\n");
     kprintf("\t\t^yclear^!       \t\tClear console\n");
     kprintf("\t\t^yhelp^!        \t\tShow this menu\n");
+    kprintf("\t\t^yrand^!        \t\tGet a random number\n");
+    kprintf("\t\t^yver^!         \t\tDisplays termOS's version\n");
 }
 
 void cmd_regs() {
@@ -100,8 +107,30 @@ void cmd_sleep() {
     sleep(3000);
 }
 
+void cmd_rand() {
+    kprintf("Your rand number (0..100) is ... ^y%d^!!\n", krand() % 100);
+}
+
 void cmd_debug() {
     u64 status = debug();
     kprintf("\nDebug ended with code %d\n", status);
     return;
 }
+
+void cmd_ver() {
+    kprintf("termOS version %s\n", TERMOS_VERSION);
+    kprintf("Dewar Kernel (x86_64), build: %s %s\n", __DATE__, __TIME__);
+    kprintf("License: GPL-3.0-or-later\n");
+}
+
+void cmd_userspace() {
+    process* init_proc = (process*)malloc(sizeof(process));
+    init_proc->pid = 1;
+    init_proc->state = RUNNING;
+    init_proc->pml4_phys = vmm_create_address_space();
+    strcpy(init_proc->name, "init");
+
+    curr_task->proc = init_proc;
+    kprintf("Trying to jump in ring 3...\n");
+    if (!exec_init(init_proc, "/init")) kprintf("Failed to jump.\n");
+}

kernel/src/shell/dbgcmd.c

@@ -1,57 +1,9 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
-// Copyright (c) 2025 0xKarinyash
-// contents of this file will be changed CONSTANTLY
-// im just testing new stuff here
+// Copyright (c) 2026 0xKarinyash
 
-#include "mm/vmm.h"
-#include <mm/pmm.h>
 #include <shell/dbgcmd.h>
 #include <drivers/console.h>
 
-extern u64* pml4_kernel;
-
-#define USER_DS (0x18 | 3)
-#define USER_CS (0x20 | 3)
-#define RFLAGS_IF 0x202
-
-void jump_to_userspace(void* entry, void* user_stack_top) {
-    __asm__ volatile (
-        "mov %0, %%ds\n"
-        "mov %0, %%es\n"
-        "mov %0, %%fs\n"
-        "mov %0, %%gs\n"
-        :: "r" ((u64)USER_DS) : "memory"
-    );
-
-    __asm__ volatile (
-        "pushq %0\n" // SS (User Data Selector)
-        "pushq %1\n" // RSP (User Stack Pointer)
-        "pushq %2\n" // RFLAGS
-        "pushq %3\n" // CS (User Code Selector)
-        "pushq %4\n" // RIP (Entry Point)
-        "iretq\n"    // jump
-        : 
-        : "r" ((u64)USER_DS),
-          "r" ((u64)user_stack_top),
-          "r" ((u64)RFLAGS_IF),
-          "r" ((u64)USER_CS),
-          "r" ((u64)entry)
-        : "memory"
-    );
-}
-
 u64 debug() {
-    void* phys_code = pmm_alloc_page();
-    void* phys_stack = pmm_alloc_page();
-    u64 virt_code = 0x400000;
-    u64 virt_stack = 0x800000;
-
-    vmm_map_page(pml4_kernel, (u64)phys_code, virt_code, PTE_PRESENT | PTE_RW | PTE_USER);
-    vmm_map_page(pml4_kernel, (u64)phys_stack, virt_stack, PTE_PRESENT | PTE_RW | PTE_USER);
-    u8* kernel_view = (u8*)(HHDM_OFFSET + phys_code);
-    kernel_view[0] = 0xEB; // jmp
-    kernel_view[1] = 0xFE; // to self
-    kprintf("Jumping to userspace. Goodbye.");
-    jump_to_userspace((void*)virt_code, (void*)(virt_stack + 4096));
     return 0;
 }

kernel/src/shell/ksh.c

@@ -33,9 +33,12 @@ typedef enum {
     TOKEN_PANIC,
     TOKEN_PANIC_UD2,
     TOKEN_PANIC_PF,
+    TOKEN_USERSPACE,
 
     TOKEN_CLEAR,
     TOKEN_BLINKING,
+    TOKEN_RAND,
+    TOKEN_VER,
 
     TOKEN_BACK,
     TOKEN_FORWARD,
@@ -56,10 +59,10 @@ static const ksh_command_map token_map[] = {
     {"sleep", TOKEN_SLEEP},
     {"dbg", TOKEN_DEBUG},
     {"regs", TOKEN_REGS},
-    {"rectest", TOKEN_RECTEST},
     {"panic", TOKEN_PANIC},
     {"ud2", TOKEN_PANIC_UD2},
     {"pf", TOKEN_PANIC_PF},
+    {"userspace", TOKEN_USERSPACE},
 
     // fun
     {"meow", TOKEN_MEOW},
@@ -69,6 +72,9 @@ static const ksh_command_map token_map[] = {
     // misc
     {"help", TOKEN_HELP},
     {"clear", TOKEN_CLEAR},
+    {"rand", TOKEN_RAND},
+    {"ver", TOKEN_VER},
+
     {nullptr, TOKEN_NULL}
 };
 
@@ -80,7 +86,7 @@ ksh_token char2token(char* token) {
 }
 
 void ksh() {
-    sched_spawn(cursor_blinker_sched_task);
+    sched_spawn(cursor_blinker_sched_task, nullptr);
     while (true) {
         kprintf("ksh_> ");
         char cmdbuff[256];
@@ -90,15 +96,17 @@ void ksh() {
 
             case TOKEN_CLEAR: console_clear((u32) console_get_colors() & 0xFFFFFFFF); break;
             case TOKEN_BLINKING: console_toggle_cursor_blink(); break;
+            case TOKEN_RAND: cmd_rand(); break;
+            case TOKEN_VER: cmd_ver(); break;
 
             case TOKEN_SLEEP: cmd_sleep(); break;
             case TOKEN_DEBUG: cmd_debug(); break;
             case TOKEN_REGS: cmd_regs(); break;
-            case TOKEN_RECTEST: rectest(0); break;
             case TOKEN_PANIC: panic("Manually initiated panic");
             case TOKEN_PANIC_UD2: __asm__ volatile ("ud2");
             case TOKEN_PANIC_PF: u64* bad_ptr = (u64*)0xDEADBEEF; *bad_ptr = 666;
-            
+            case TOKEN_USERSPACE: cmd_userspace(); break;
+
             case TOKEN_SPLASH: show_splash(console_get_context()); break;
             case TOKEN_KFETCH: cmd_kfetch(); break;
             case TOKEN_MEOW: cmd_meow(); break;

userspace/CMakeLists.txt

@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.20)
+project(termOSuserspace LANGUAGES C ASM_NASM)
+
+set(CMAKE_C_STANDARD 23)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+set(CMAKE_C_EXTENSIONS OFF)
+
+message(STATUS "Building termOS's userspace")
+
+add_subdirectory(init)

userspace/init/CMakeLists.txt

@@ -0,0 +1,32 @@
+cmake_minimum_required(VERSION 3.20)
+project(termOSinit LANGUAGES C)
+
+set(CMAKE_C_STANDARD 23)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+set(CMAKE_C_EXTENSIONS OFF)
+
+message(STATUS "Building termOS's init")
+
+file(GLOB_RECURSE INIT_SOURCES CMAKE_CONFIGURE_DEPENDS
+    "src/*.asm"
+    "src/*.c"
+)
+
+add_executable(init ${INIT_SOURCES})
+set_target_properties(init PROPERTIES
+    SUFFIX ""
+    LINKER_LANGUAGE C 
+)
+
+target_link_options(init PRIVATE
+    -nostdlib
+    -static
+    -Wl,--oformat=binary
+    -Wl,-Ttext=0x400000
+    -Wl,-e,start
+)
+
+add_custom_command(TARGET init POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:init> ${CMAKE_SOURCE_DIR}/initramfs/init
+    COMMENT "Installing init binary to initramfs"
+)

userspace/init/src/crt0.asm

@@ -0,0 +1,10 @@
+[bits 64]
+
+section .text
+global start
+extern main
+
+start:
+    call main
+.hang:
+    jmp .hang

userspace/init/src/main.c

@@ -0,0 +1,16 @@
+static inline void sys_write(const char* str) {
+    __asm__ volatile (
+        "mov $2, %%rax\n\t"   
+        "mov %0, %%rdi\n\t"
+        "syscall"
+        :
+        : "r"(str)
+        : "rax", "rdi", "rcx", "r11", "memory" 
+    );
+}
+
+int main() {
+    sys_write("Meowww!!!\n");
+    sys_write("Nyaaaaa");
+    for (int i = 0; i < 100; i++) sys_write("a"); 
+}