From 782b3c8563b2aacfe8f48a49fc6de7cbc26c4861 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Thu, 30 Jul 2026 13:59:59 +0200
Subject: kernel: implement dev zero and null

---
 kernel/kapi/devices/device_registry.cpp | 10 +++++++++-
 kernel/kapi/devices/error.cpp           | 17 +++++++++++++----
 2 files changed, 22 insertions(+), 5 deletions(-)

(limited to 'kernel/kapi')

diff --git a/kernel/kapi/devices/device_registry.cpp b/kernel/kapi/devices/device_registry.cpp
index 80ddde65..080ae39b 100644
--- a/kernel/kapi/devices/device_registry.cpp
+++ b/kernel/kapi/devices/device_registry.cpp
@@ -1,5 +1,6 @@
 #include <kapi/devices/device_registry.hpp>
 
+#include <kapi/devices/bus.hpp>
 #include <kapi/devices/device.hpp>
 #include <kapi/system.hpp>
 
@@ -48,7 +49,14 @@ namespace kapi::devices
       return false;
     }
 
-    kstd::println("[OS:DEV] Registering device {}", device->name());
+    if (device->facet<bus>())
+    {
+      kstd::println("[OS:DEV] Registering bus {}", device->name());
+    }
+    else
+    {
+      kstd::println("[OS:DEV] Registering device {}", device->name());
+    }
 
     auto added = false;
     {
diff --git a/kernel/kapi/devices/error.cpp b/kernel/kapi/devices/error.cpp
index 9d814fbe..40320551 100644
--- a/kernel/kapi/devices/error.cpp
+++ b/kernel/kapi/devices/error.cpp
@@ -3,7 +3,6 @@
 #include <kstd/system_error.hpp>
 
 #include <string_view>
-#include <utility>
 
 namespace kapi::devices
 {
@@ -23,6 +22,10 @@ namespace kapi::devices
         {
           case driver_match_errc::no_match:
             return "driver does not match this device";
+          case driver_match_errc::no_device_signature:
+            return "missing device signature";
+          case driver_match_errc::invalid_device_signature:
+            return "device signature is invalid";
           default:
             return "unknown driver matching error";
         }
@@ -30,11 +33,17 @@ namespace kapi::devices
 
       [[nodiscard]] auto default_error_condition(int value) const noexcept -> kstd::error_condition override
       {
-        if (value == std::to_underlying(driver_match_errc::no_match))
+        switch (static_cast<driver_match_errc>(value))
         {
-          return make_error_condition(kstd::errc::not_supported);
+          case driver_match_errc::no_match:
+          case driver_match_errc::no_device_signature:
+            return make_error_condition(kstd::errc::not_supported);
+            break;
+          case driver_match_errc::invalid_device_signature:
+            return make_error_condition(kstd::errc::invalid_argument);
+          default:
+            return kstd::error_category::default_error_condition(value);
         }
-        return kstd::error_category::default_error_condition(value);
       }
 
     } constexpr driver_match_category_instance{};
-- 
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