From f50815110789a0f8f6e5ca66ffd49b26578791a9 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Mon, 6 Apr 2026 18:43:28 +0200
Subject: kernel: generalize CPU discovery

---
 kernel/CMakeLists.txt      |  1 +
 kernel/kapi/devices.cpp    | 11 +++------
 kernel/kapi/platform.cpp   | 32 +++++++++++++++++++++++++
 kernel/src/devices/cpu.cpp | 58 +++-------------------------------------------
 4 files changed, 39 insertions(+), 63 deletions(-)
 create mode 100644 kernel/kapi/platform.cpp

(limited to 'kernel')

diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index 6e081bd..22513ea 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -9,6 +9,7 @@ add_library("kernel_objs" OBJECT
     "kapi/devices/device.cpp"
     "kapi/interrupts.cpp"
     "kapi/memory.cpp"
+    "kapi/platform.cpp"
     "kapi/system.cpp"
 
     # KSTD OS Implementation
diff --git a/kernel/kapi/devices.cpp b/kernel/kapi/devices.cpp
index b2911b0..dad1fe4 100644
--- a/kernel/kapi/devices.cpp
+++ b/kernel/kapi/devices.cpp
@@ -1,6 +1,5 @@
 #include "kapi/devices.hpp"
 
-#include "kapi/acpi.hpp"
 #include "kapi/system.hpp"
 
 #include "kernel/devices/cpu.hpp"
@@ -38,13 +37,9 @@ namespace kapi::devices
     register_device(bus);
     bus.init();
 
-    auto madt = kapi::acpi::get_table("APIC");
-    if (madt)
-    {
-      auto cpu_major = allocate_major_number();
-      auto cpu = kstd::make_unique<kernel::devices::cpu>(cpu_major);
-      bus.add_child(std::move(cpu));
-    }
+    auto cpu_major = allocate_major_number();
+    auto cpu = kstd::make_unique<kernel::devices::cpu>(cpu_major);
+    bus.add_child(std::move(cpu));
   }
 
   auto get_root_bus() -> bus &
diff --git a/kernel/kapi/platform.cpp b/kernel/kapi/platform.cpp
new file mode 100644
index 0000000..deb72de
--- /dev/null
+++ b/kernel/kapi/platform.cpp
@@ -0,0 +1,32 @@
+#include "kapi/platform.hpp"
+
+#include "kapi/devices.hpp"
+
+#include "kernel/devices/cpu.hpp"
+
+#include <kstd/memory>
+
+#include <cstdint>
+#include <utility>
+
+namespace kapi::platform
+{
+
+  auto cpu_detected(kapi::devices::bus & bus, std::uint64_t hardware_id, bool is_bsp) -> bool
+  {
+    auto static const core_major = kapi::devices::allocate_major_number();
+    auto static const interrupt_controller_major = kapi::devices::allocate_major_number();
+    auto static core_index = 0uz;
+
+    auto core = kstd::make_unique<kernel::devices::cpu::core>(core_major, core_index, hardware_id, is_bsp);
+    auto lapic = kapi::platform::create_core_interrupt_controller(interrupt_controller_major, core_index, hardware_id);
+
+    core->add_child(std::move(lapic));
+    bus.add_child(std::move(core));
+
+    ++core_index;
+
+    return true;
+  }
+
+}  // namespace kapi::platform
\ No newline at end of file
diff --git a/kernel/src/devices/cpu.cpp b/kernel/src/devices/cpu.cpp
index 7147368..eb10d74 100644
--- a/kernel/src/devices/cpu.cpp
+++ b/kernel/src/devices/cpu.cpp
@@ -1,64 +1,16 @@
 #include "kernel/devices/cpu.hpp"
 
-#include "kapi/acpi.hpp"
 #include "kapi/devices.hpp"
+#include "kapi/platform.hpp"
 
-#include <kstd/memory>
 #include <kstd/print>
 
 #include <cstddef>
 #include <cstdint>
-#include <utility>
 
 namespace kernel::devices
 {
 
-  namespace
-  {
-
-    auto process_madt(kstd::observer_ptr<kapi::acpi::madt_header const> madt, kapi::devices::bus & cpu) -> void
-    {
-      auto static const core_major = kapi::devices::allocate_major_number();
-      auto static const lapic_major = kapi::devices::allocate_major_number();
-
-      auto lapic_address = madt->local_interrupt_controller_address();
-
-      auto const * current = reinterpret_cast<std::byte const *>(madt.get()) + sizeof(kapi::acpi::madt_header);
-      auto const * end = reinterpret_cast<std::byte const *>(madt.get()) + madt->length();
-
-      auto bsp_found = false;
-      auto core_index = 0;
-
-      while (current < end)
-      {
-        auto const * sub_table = reinterpret_cast<kapi::acpi::madt_subtable_header const *>(current);
-        if (sub_table->type() == 0)
-        {
-          auto const * local_apic = reinterpret_cast<kapi::acpi::madt_local_apic const *>(sub_table);
-          if (local_apic->flags() & 0b11)
-          {
-            auto is_bsp = !bsp_found;
-            bsp_found = true;
-
-            auto apic_id = local_apic->apic_id();
-            auto core = kstd::make_unique<kernel::devices::cpu::core>(core_major, core_index, apic_id, is_bsp);
-            auto lapic = kapi::acpi::create_local_interrupt_controller(lapic_major, core_index, apic_id, lapic_address);
-
-            core->add_child(std::move(lapic));
-            cpu.add_child(std::move(core));
-
-            ++core_index;
-          }
-        }
-
-        current += sub_table->length();
-      }
-
-      kstd::println("[OS:DEV] Discovered {} CPU cores", core_index);
-    }
-
-  }  // namespace
-
   cpu::core::core(std::size_t major_number, std::size_t minor_number, std::uint64_t hardware_id, bool is_bsp)
       : kapi::devices::bus{major_number, minor_number, "cpu_core"}
       , m_hardware_id{hardware_id}
@@ -81,16 +33,12 @@ namespace kernel::devices
 
   auto cpu::probe() -> bool
   {
-    auto madt = kapi::acpi::get_table("APIC");
-    if (!madt)
+    if (!kapi::platform::discover_cpu_topology(*this))
     {
-      kstd::println("[OS:DEV] Failed to find ACPI APIC table");
+      kstd::println("[OS:DEV] Failed to discover CPU topology");
       return false;
     }
 
-    auto madt_header = static_cast<kapi::acpi::madt_header const *>(madt.get());
-    process_madt(kstd::make_observer(madt_header), *this);
-
     return true;
   }
 
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