kern: add new unknown DebugThreadParam

libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp

@@ -341,6 +341,7 @@ namespace ams::kern {
             bool                                                m_debug_attached;
             s8                                                  m_priority_inheritance_count;
             bool                                                m_resource_limit_release_hint;
+            bool                                                m_debug_unknown5;
         public:
             constexpr explicit KThread(util::ConstantInitializeTag)
                 : KAutoObjectWithSlabHeapAndContainer<KThread, KWorkerTask>(util::ConstantInitialize), KTimerTask(util::ConstantInitialize),
@@ -683,6 +684,9 @@ namespace ams::kern {
             constexpr void SetDebugAttached() { m_debug_attached = true; }
             constexpr bool IsAttachedToDebugger() const { return m_debug_attached; }
 
+            constexpr void SetDebugUnknown5(bool value) { m_debug_unknown5 = value; }
+            constexpr bool IsDebugUnknown5() const { return m_debug_unknown5; }
+
             void AddCpuTime(s32 core_id, s64 amount) {
                 m_cpu_time += amount;
                 /* TODO: Debug kernels track per-core tick counts. Should we? */

libraries/libmesosphere/source/kern_k_process.cpp

@@ -970,6 +970,9 @@ namespace ams::kern {
         /* Initialize the thread. */
         R_TRY(KThread::InitializeUserThread(main_thread, reinterpret_cast<KThreadFunction>(GetVoidPointer(this->GetEntryPoint())), 0, stack_top, priority, m_ideal_core_id, this));
 
+        /* TODO: what is this? */
+        main_thread->SetDebugUnknown5(true);
+
         /* Register the thread, and commit our reservation. */
         KThread::Register(main_thread);
         thread_reservation.Commit();

libraries/libmesosphere/source/svc/kern_svc_debug.cpp

@@ -429,6 +429,11 @@ namespace ams::kern::svc {
                         *out_32 = affinity_mask;
                     }
                     break;
+                case ams::svc::DebugThreadParam_Unknown5:
+                    {
+                        *out_32 = thread->IsDebugUnknown5();
+                    }
+                    break;
                 default:
                     R_THROW(ams::svc::ResultInvalidEnumValue());
             }