wip: IPC and Runtime

.gitignore

@@ -6,3 +6,4 @@ compile_commands.json
 ide-swift-toolchain.txt
 .cache
 .zed
+Runtime/.clangd

Kernel/Include/Arch/CPU.h

@@ -2,6 +2,7 @@
 // Copyright (c) 2026 0xKSor
 
 #pragma once
+#include "Arch/Exceptions.h"
 #include <Types.h>
 
 static inline void CPUYield() {
@@ -63,7 +64,7 @@ static inline void CPUEnableMMU(Address l0PhysicalAddress) {
     // MAIR_EL1 (Memory Attribute Indirection Register)
     // kPTENormalMem is index 0 and kPTEDeviceMem is index 1
     // 0xFF = Normal, 0x00 = Device
-    UInt64 mair = (0xFFULL << 0) | (0x00ULL << 8); 
+    UInt64 mair = (0xFFULL << 0) | (0x00ULL << 8);
 
     // TCR_EL1 (Translation Control Register)
     // configures the mmu for 4kb pages and 48bit virtual addresses
@@ -82,11 +83,11 @@ static inline void CPUEnableMMU(Address l0PhysicalAddress) {
         "msr tcr_el1, %1\n"
         "msr ttbr0_el1, %2\n"  // set userspace root
         "msr ttbr1_el1, %2\n"  // set kernelspace root
-        "tlbi vmalle1is\n"  
+        "tlbi vmalle1is\n"
         "isb\n"                // Instruction Synchronization Barrier
         :: "r"(mair), "r"(tcr), "r"(l0PhysicalAddress) : "memory"
     );
-            
+
     // turn on the MMU in SCTLR_EL1 (System Control Register)
     // Bit 0 = M (MMU Enable), Bit 2 = C (Data Cache Enable), Bit 12 = I (Instruction Cache Enable)
     UInt64 sctlr;
@@ -111,4 +112,13 @@ static inline void CPUSwitchAddressSpace(Address l0Physical) {
     );
 }
 
-#define CPUException(number) __asm__ volatile ("svc %0" :: "i" (number) : "memory")
+static inline void CPUCopyIPCRegisters(ExceptionsContext* source, ExceptionsContext* destination) {
+    destination->x2 = source->x2;
+    destination->x3 = source->x3;
+    destination->x4 = source->x4;
+    destination->x5 = source->x5;
+    destination->x6 = source->x6;
+    destination->x7 = source->x7;
+}
+
+#define CPUException(number) __asm__ volatile ("svc %0" :: "i" (number) : "memory")

Kernel/Include/Arch/IO.h

@@ -14,4 +14,4 @@ static inline UInt32 IOAddressRead32(Address address) {
     UInt32 value = *(volatile UInt32*)address;
     __asm__ volatile ("dsb ld" ::: "memory"); // wait till my read is finished physically
     return value;
-}
+}

Kernel/Include/OS/IPC.h

@@ -0,0 +1,7 @@
+#pragma once
+#include "Arch/Exceptions.h"
+#include <Types.h>
+#include <OS/Scheduler.h>
+
+UInt64 IPCSend(OSTask* sender, UInt64 handleID, UInt64 data);
+void IPCReceive(ExceptionsContext* receiverFrame);

Kernel/Include/OS/Modules.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <Types.h>
 #include "../Common/bootinfo.h"
+#include <OS/Scheduler.h>
 
-void ModuleLoad(BootModule* module);
+OSTask* ModuleLoad(BootModule* module);

Kernel/Include/OS/Scheduler.h

@@ -4,12 +4,31 @@
 #pragma once
 #include <Types.h>
 
+typedef enum {
+    kOSHandleTypeNone = 0,
+    kOSHandleTypeTask
+} OSHandleType;
+
+typedef struct {
+    OSHandleType type;
+    Pointer object;
+} OSHandle;
+
+enum {
+    kOSSchedulerTaskStackSize = 16 * 1024,
+    kOSSchedulerExceptionNumber = 0xF0F0,
+    kOSMaxHandlesPerProcess = 256,
+};
+
 typedef enum OSTaskState {
     OSTaskStateDead,
     OSTaskStateRunning,
     OSTaskStateReady,
     OSTaskStateBlocked,
     OSTaskStateSleeping,
+
+    OSTaskStateBlockedReceive,
+    OSTaskStateBlockedSend,
 } OSTaskState;
 
 typedef struct OSProcess {
@@ -20,11 +39,12 @@ typedef struct OSProcess {
     Address heapCurrent;
     struct OSProcess* parent;
     ASCII name[32];
+
+    OSHandle handles[kOSMaxHandlesPerProcess];
 } OSProcess;
 
 typedef struct OSTask {
     Address stackPointer;
-    struct OSTask* next;
     UInt32 id;
     UInt32 sleepTicks;
     OSTaskState state;
@@ -32,12 +52,10 @@ typedef struct OSTask {
     Pointer kernelStackBase;
     OSProcess* process;
     Int32 waitingForProcessId;
-} OSTask;
 
-enum {
-    kOSSchedulerTaskStackSize = 16 * 1024,
-    kOSSchedulerExceptionNumber = 0xF0F0
-};
+    struct OSTask* next;
+    struct OSTask* senderWaiting;
+} OSTask;
 
 extern UInt32 gOSSchedulerNextProcessID;
 
@@ -46,3 +64,7 @@ OSTask* SchedulerSpawn(void(*entryPoint)(), OSProcess* owner, Boolean isUser, Ad
 Address SchedulerNext(Address stackPointer);
 void SchedulerYield(UInt64 ticks);
 UInt64 SchedulerGetNextProcessID();
+void SchedulerBlockCurrentTask(UInt32 newState);
+OSTask* SchedulerGetCurrentTask();
+Int32 SchedulerProcessAllocateHandle(OSProcess* process, OSHandleType type, Pointer object);
+Pointer SchedulerProcessGetHandle(OSProcess* process, UInt32 handleId, OSHandleType expectedType);

Kernel/Include/OS/Syscall.h

@@ -0,0 +1,10 @@
+#pragma once
+#include <Types.h>
+#include <Arch/Exceptions.h>
+
+enum Syscalls {
+    kSyscallSend,
+    kSyscallReceive,
+};
+
+Address SyscallDispatch(ExceptionsContext* frame);

Kernel/Source/Arch/Exceptions.c

@@ -5,6 +5,7 @@
 #include <Arch/GIC.h>
 #include <OS/Panic.h>
 #include <OS/Scheduler.h>
+#include <OS/Syscall.h>
 
 Address ExceptionsHandler(ExceptionsContext* frame, ExceptionsType type) {
     if (type == ExceptionsIRQEl1h || type == ExceptionsIRQEl064) return GICDispatch(frame, type);
@@ -13,14 +14,9 @@ Address ExceptionsHandler(ExceptionsContext* frame, ExceptionsType type) {
         UInt32 class = (esr >> 26) & 0x3F;
         UInt32 syndrome = esr & 0x1FFFFFF;
 
-        if (class == 0x11 || class == 0x15) {
-            if (syndrome == kOSSchedulerExceptionNumber) {
-                return SchedulerNext((Address)frame);
-            }
-        }
-
-        if (class == 0x15 && syndrome == 0) {
-            OSPanic("Hi from userspace!!");
+        if (class == 0x15) {
+            if (syndrome == kOSSchedulerExceptionNumber) return SchedulerNext((Address)frame);
+            if (syndrome == 0) return SyscallDispatch(frame);
         }
     }
     OSPanicException(frame);

Kernel/Source/KernelMain.c

@@ -40,8 +40,7 @@ void KernelMain(Bootinfo* bootinfo) {
     SchedulerInitialize();
 
     for (UInt32 i = 0; i < bootinfo->moduleCount; i++) {
-        ModuleLoad(&bootinfo->modules[i]); // TODO: make some sort of priority of loading modules
-                                            // like init first then uart then fb ...
+        ModuleLoad(&bootinfo->modules[i]); // TODO: priority
     }
 
     OSLog("Kernel initialized.\n");

Kernel/Source/OS/IPC.c

@@ -0,0 +1,46 @@
+#include <OS/IPC.h>
+#include <OS/Scheduler.h>
+#include <Arch/CPU.h>
+#include <Arch/Exceptions.h>
+
+UInt64 IPCSend(OSTask* sender, UInt64 handleID, UInt64 data) {
+    if (handleID == 0) return -1;
+    OSProcess* currentProcess = sender->process;
+    OSTask* targetTask = (OSTask*)SchedulerProcessGetHandle(currentProcess, handleID, kOSHandleTypeTask);
+    if (!targetTask) return -1;
+
+    if (targetTask->state == OSTaskStateBlockedReceive) {
+        ExceptionsContext* receiverContext = (ExceptionsContext*)targetTask->stackPointer;
+        receiverContext->x1 = data;
+        receiverContext->x0 = currentProcess->id;
+
+        targetTask->state = OSTaskStateRunning;
+        return 0;
+    }
+
+    if (targetTask->senderWaiting != nullptr) return -2;
+
+    targetTask->senderWaiting = sender;
+
+    SchedulerBlockCurrentTask(OSTaskStateBlockedSend);
+    return 0;
+}
+
+void IPCReceive(ExceptionsContext* receiverFrame) {
+    OSTask* receiver = SchedulerGetCurrentTask();
+
+    if (receiver->senderWaiting != nullptr) {
+        OSTask* sender = receiver->senderWaiting;
+
+        ExceptionsContext* senderContext = (ExceptionsContext*)sender->stackPointer;
+
+        receiverFrame->x1 = senderContext->x1;       // Data
+        receiverFrame->x0 = sender->process->id;     // Sender ID
+
+        receiver->senderWaiting = nullptr;
+        sender->state = OSTaskStateRunning;
+        return;
+    }
+
+    SchedulerBlockCurrentTask(OSTaskStateBlockedReceive);
+}

Kernel/Source/OS/Modules.c

@@ -7,7 +7,7 @@
 #include <Arch/CPU.h>
 #include "../Common/bootinfo.h"
 
-void ModuleLoad(BootModule* module) {
+OSTask* ModuleLoad(BootModule* module) {
     OSProcess* userProc = HeapAllocate(sizeof(OSProcess));
     MemorySet(userProc, 0, sizeof(OSProcess));
     userProc->id = SchedulerGetNextProcessID();
@@ -56,8 +56,8 @@ void ModuleLoad(BootModule* module) {
 
     if ((Address)userEntryPoint == 0x0) {
         OSLog("Skipping module %s: entry point is 0x0.\n", module->name);
-        return;
+        return nullptr;
     }
 
-    SchedulerSpawn(userEntryPoint, userProc, true, userStackVirt + kVMPageSize);
+    return SchedulerSpawn(userEntryPoint, userProc, true, userStackVirt + kVMPageSize);
 }

Kernel/Source/OS/Scheduler.c

@@ -69,6 +69,7 @@ OSTask* SchedulerSpawn(void(*entryPoint)(), OSProcess* owner, Boolean isUser, Ad
     task->waitingForProcessId = -1;
 
     task->next = gOSSchedulerCurrentTask->next;
+    task->senderWaiting = nullptr;
     gOSSchedulerCurrentTask->next = task;
 
     return task;
@@ -126,3 +127,30 @@ void SchedulerYield(UInt64 ticks) {
 UInt64 SchedulerGetNextProcessID() {
     return gOSSchedulerNextProcessID++;
 }
+
+void SchedulerBlockCurrentTask(UInt32 newState) {
+    gOSSchedulerCurrentTask->state = newState;
+    CPUException(kOSSchedulerExceptionNumber);
+}
+
+OSTask* SchedulerGetCurrentTask() {
+    return gOSSchedulerCurrentTask;
+}
+
+Int32 SchedulerProcessAllocateHandle(OSProcess* process, OSHandleType type, Pointer object) {
+    for (Int32 i = 1; i < kOSMaxHandlesPerProcess; i++) {
+        if (process->handles[i].type == kOSHandleTypeNone) {
+            process->handles[i].type = type;
+            process->handles[i].object = object;
+            return i;
+        }
+    }
+    return -1;
+}
+
+Pointer SchedulerProcessGetHandle(OSProcess* process, UInt32 handleId, OSHandleType expectedType) {
+    if (handleId == 0 || handleId >= kOSMaxHandlesPerProcess) return nullptr;
+    OSHandle* handle = &process->handles[handleId];
+    if (handle->type != expectedType) return nullptr;
+    return handle->object;
+}

Kernel/Source/OS/Syscall.c

@@ -0,0 +1,25 @@
+#include <OS/Syscall.h>
+#include <OS/IPC.h>
+#include <OS/Scheduler.h>
+#include <OS/Panic.h>
+#include <Arch/Exceptions.h>
+
+Address SyscallDispatch(ExceptionsContext* frame) {
+    UInt64 syscallNumber = frame->x8;
+    OSTask* current = SchedulerGetCurrentTask();
+
+    switch (syscallNumber) {
+        case kSyscallSend:
+            frame->x0 = IPCSend(current, frame->x0, frame->x1);
+            break;
+        case kSyscallReceive:
+            IPCReceive(frame);
+            break;
+        default:
+            frame->x0 = -1;
+            break;
+    }
+
+    if (current->state != OSTaskStateRunning) return SchedulerNext((Address)frame);
+    return (Address)frame;
+}

Runtime/Common/aarch64.cmake

@@ -56,3 +56,7 @@ find_program(LLVM_OBJCOPY NAMES llvm-objcopy objcopy
         /opt/homebrew/bin
     REQUIRED
 )
+
+set(CMAKE_C_FLAGS_INIT "-ffreestanding -mgeneral-regs-only -std=c23")
+
+set(CMAKE_EXE_LINKER_FLAGS_INIT "-nostdlib -static -no-pie -z max-page-size=0x1000 --no-dynamic-linker -T ${CMAKE_CURRENT_LIST_DIR}/linker.ld -Ttext=0x400000")

Runtime/Common/ksOS_SDK.cmake

@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+# Copyright (c) 2026 0xKSor
+
+set(KSOS_SYSROOT_SRC "${CMAKE_CURRENT_LIST_DIR}/..")
+set(BUILD_DIR $ENV{BUILD_DIR})
+if(NOT BUILD_DIR)
+  set(BUILD_DIR "${CMAKE_CURRENT_LIST_DIR}/../../.build")
+endif()
+
+set(KSOS_LIB_DIR "${BUILD_DIR}/Runtime/System/libksOS")
+
+function(add_ksos_executable TARGET_NAME)
+  add_executable(${TARGET_NAME}
+        "${KSOS_SYSROOT_SRC}/System/libksOS/Source/crt0.S"
+        ${ARGN}
+    )
+
+  target_include_directories(${TARGET_NAME} PRIVATE
+        "${KSOS_SYSROOT_SRC}/System/libksOS/Include"
+    )
+
+  target_link_directories(${TARGET_NAME} PRIVATE
+        "${KSOS_LIB_DIR}"
+    )
+
+  target_link_libraries(${TARGET_NAME} PRIVATE
+        ksOS
+    )
+endfunction()

Runtime/System/Init/CMakeLists.txt

@@ -4,44 +4,16 @@
 cmake_minimum_required(VERSION 3.20)
 project(ksOS_init LANGUAGES C ASM)
 
+include("${CMAKE_CURRENT_SOURCE_DIR}/../../Common/ksOS_SDK.cmake")
 
 file(GLOB_RECURSE INIT_SOURCES CMAKE_CONFIGURE_DEPENDS
     ${CMAKE_CURRENT_SOURCE_DIR}/Source/*.S
     ${CMAKE_CURRENT_SOURCE_DIR}/Source/*.c
 )
 
-add_executable(init ${INIT_SOURCES})
+add_ksos_executable(Init ${INIT_SOURCES})
 
-target_include_directories(init PRIVATE
-    ${CMAKE_CURRENT_SOURCE_DIR}/Source
-    ${CMAKE_CURRENT_SOURCE_DIR}/../../Common
-)
-
-target_compile_options(init PRIVATE
-    $<$<COMPILE_LANGUAGE:C>:
-        -std=c23
-        -fno-stack-protector
-        -fno-builtin
-        -Wall
-        -Wextra
-    >
-    -ffreestanding
-    -g
-    -mgeneral-regs-only
-)
-
-target_link_options(init PRIVATE
-    -nostdlib
-    -static
-    -no-pie
-    -T "${CMAKE_CURRENT_SOURCE_DIR}/../../Common/linker.ld"
-    -Ttext=0x400000
-    -e _start
-    -z max-page-size=0x1000
-    --no-dynamic-linker
-)
-
-set_target_properties(init PROPERTIES
+set_target_properties(Init PROPERTIES
     OUTPUT_NAME "Init"
     RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}"
 )

Runtime/System/Init/Source/main.c

@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 // Copyright (c) 2026 0xKSor
 
-void main(void) {
-    __asm__ volatile(
-        "svc #0\n"
-        "b .\n"
-    );
+#include <ksOS/Syscall.h>
+
+int main(void) {
+    SysSend(1, 0xa0a0a0a0a);
+    while (1) {}
 }

Runtime/System/Test/CMakeLists.txt

@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+# Copyright (c) 2026 0xKSor
+
+cmake_minimum_required(VERSION 3.20)
+project(ksOS_test LANGUAGES C ASM)
+
+include("${CMAKE_CURRENT_SOURCE_DIR}/../../Common/ksOS_SDK.cmake")
+
+file(GLOB_RECURSE INIT_SOURCES CMAKE_CONFIGURE_DEPENDS
+    ${CMAKE_CURRENT_SOURCE_DIR}/Source/*.S
+    ${CMAKE_CURRENT_SOURCE_DIR}/Source/*.c
+)
+
+add_ksos_executable(Init ${INIT_SOURCES})
+
+set_target_properties(Init PROPERTIES
+    OUTPUT_NAME "Test"
+    RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}"
+)

Runtime/System/Test/Source/main.c

@@ -0,0 +1,9 @@
+#include <ksOS/Syscall.h>
+
+
+int main() {
+    IPCMessage message = SysRecive();
+    if (message.data == 0xa0a0a0a0a) {
+        Sys228();
+    }
+}

Runtime/System/libksOS/CMakeLists.txt

@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+cmake_minimum_required(VERSION 3.20)
+project(libksOS LANGUAGES C ASM)
+
+file(GLOB_RECURSE LIB_SOURCES CMAKE_CONFIGURE_DEPENDS
+    ${CMAKE_CURRENT_SOURCE_DIR}/*.c
+)
+
+add_library(ksOS STATIC ${LIB_SOURCES})
+
+target_include_directories(ksOS PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/Include
+)
+
+target_compile_options(ksOS PRIVATE
+    -std=c23 -fno-stack-protector -fno-builtin -Wall -Wextra
+)

Runtime/System/libksOS/Include/ksOS/Syscall.h

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKSor
+
+#pragma once
+#include <ksOS/Types.h>
+
+enum {
+    kSyscallSend = 1,
+    kSyscallReceive,
+};
+
+typedef struct IPCMessage {
+    UInt64 senderID;
+    UInt64 data;
+} IPCMessage;
+
+static inline UInt64 SysSend(UInt64 handleID, UInt64 data) {
+    register UInt64 x8 __asm__("x8") = kSyscallSend;
+    register UInt64 x0 __asm__("x0") = handleID;
+    register UInt64 x1 __asm__("x1") = data;
+
+    __asm__ volatile(
+        "svc #0\n"
+        : "+r" (x0)
+        : "r" (x1), "r" (x8)
+        : "memory", "cc"
+    );
+    return x0;
+}
+
+static inline IPCMessage SysRecive(void) {
+    register UInt64 x8 __asm__("x8") = kSyscallReceive;
+    register UInt64 x0 __asm__("x0");
+    register UInt64 x1 __asm__("x1");
+
+    __asm__ volatile(
+        "svc #0\n"
+        : "=r" (x0), "=r" (x1)
+        : "r" (x8)
+        : "memory", "cc"
+    );
+
+    struct IPCMessage msg = { x0, x1 };
+    return msg;
+}
+
+static inline void Sys228(void) {
+    register UInt64 x8 __asm__("x8") = 228;
+    __asm__ volatile(
+        "svc #0\n"
+        :
+        : "r" (x8)
+        : "memory", "cc"
+    );
+}

Runtime/System/libksOS/Include/ksOS/Types.h

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKSor
+
+#pragma once
+
+#if defined(NDEBUG) || defined(__OPTIMIZE__)
+    #define IS_RELEASE 1
+#else
+    #define IS_RELEASE 0
+#endif
+
+typedef unsigned char      UInt8;
+typedef unsigned short     UInt16;
+typedef unsigned int       UInt32;
+typedef unsigned long long UInt64;
+typedef unsigned long long UInt;
+
+typedef void* Pointer;
+typedef UInt Address;
+typedef UInt32 Address32;
+typedef UInt8* BytePointer;
+typedef UInt8* MemoryPointer;
+
+typedef signed char        Int8;
+typedef signed short       Int16;
+typedef signed int         Int32;
+typedef signed long long   Int64;
+typedef int Int;
+
+typedef UInt64 Size;
+typedef char ASCII;
+
+typedef _Bool Boolean;

Runtime/System/libksOS/Source/Syscall.c

@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (c) 2026 0xKSor

Runtime/System/libksOS/Source/crt0.S

@@ -4,14 +4,9 @@
 .section .text.entry, "ax"
 .global _start
 _start:
-    // Set up stack pointer (8KB stack)
     adrp x0, stack_top
     add  sp, x0, :lo12:stack_top
-
-    // Jump to C main
     bl   main
-
-    // If main returns, loop forever
     b    .
 
 .section .bss, "aw", @nobits

Runtime/justfile

@@ -95,8 +95,22 @@ _default:
         exit 0
     fi
 
+    # libksOS MUST be built first — everyone depends on it
     for dir in "${projects[@]}"; do
         name=$(basename "${dir}")
+        if [ "${name}" = "libksOS" ]; then
+            echo ""
+            echo "  📦 ${CATEGORY}/${name}"
+            just --quiet _build_cmake "${dir}" "${CATEGORY}/${name}"
+            break
+        fi
+    done
+
+    for dir in "${projects[@]}"; do
+        name=$(basename "${dir}")
+        if [ "${name}" = "libksOS" ]; then
+            continue
+        fi
         echo ""
         echo "  📦 ${CATEGORY}/${name}"
 
@@ -111,6 +125,7 @@ _default:
 
 @build:
     @echo "🛠️ Building Runtime..."
+    @just --quiet clangd
     @mkdir -p {{ RUNTIME_BUILD_DIR }}/System
     @mkdir -p {{ RUNTIME_BUILD_DIR }}/Apps
     @just --quiet _discover_and_build System
@@ -122,3 +137,13 @@ _default:
     @rm -rf {{ TEMP_DIR }}/Runtime
     @rm -rf {{ RUNTIME_BUILD_DIR }}
     @echo "🧹 Runtime cleaned"
+
+@clangd:
+    #!/usr/bin/env bash
+    set -e
+    RUNTIME_DIR="{{ justfile_directory() }}"
+    INCLUDE_DIR="${RUNTIME_DIR}/System/libksOS/Include"
+
+    printf 'CompileFlags:\n  Add:\n    - -xc\n    - --target=aarch64-none-elf\n    - -ffreestanding\n    - -I%s\n' "${INCLUDE_DIR}" > "${RUNTIME_DIR}/.clangd"
+
+    echo "✅ Generated ${RUNTIME_DIR}/.clangd"