kern: improve resource region size definitions/calculations

libraries/libmesosphere/source/kern_k_memory_layout.cpp

@@ -168,6 +168,19 @@ namespace ams::kern {
         }
     }
 
+    size_t KMemoryLayout::GetResourceRegionSizeForInit() {
+        /* Calculate resource region size based on whether we allow extra threads. */
+        const bool use_extra_resources = KSystemControl::Init::ShouldIncreaseThreadResourceLimit();
+        size_t resource_region_size = KernelResourceSize + (use_extra_resources ? KernelSlabHeapAdditionalSize : 0);
+
+        /* 10.0.0 reduced the slab heap gaps by 64K. */
+        if (kern::GetTargetFirmware() < ams::TargetFirmware_10_0_0) {
+            resource_region_size += (KernelSlabHeapGapsSizeDeprecated - KernelSlabHeapGapsSize);
+        }
+
+        return resource_region_size;
+    }
+
     namespace init {
 
         namespace {