Kernel: root command line option can be specified as an UUID

Format is the same as in linux
root=UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

This makes it easier to boot when computer has multiple disks installed

BAN/include/BAN/GUID.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include <BAN/Optional.h>
-#include <BAN/StringView.h>
+#include <BAN/String.h>
 
 #include <string.h>
 
@@ -19,6 +19,54 @@ namespace BAN
 		{
 			return memcmp(this, &other, sizeof(GUID)) == 0;
 		}
+
+		BAN::ErrorOr<BAN::String> to_string() const
+		{
+			char buffer[37];
+			char* ptr = buffer;
+
+			const auto append_hex_nibble =
+				[&ptr](uint8_t nibble)
+				{
+					if (nibble < 10)
+						*ptr++ = '0' + nibble;
+					else
+						*ptr++ = 'A' + nibble - 10;
+				};
+
+			const auto append_hex_byte =
+				[&append_hex_nibble](uint8_t byte)
+				{
+					append_hex_nibble(byte >> 4);
+					append_hex_nibble(byte & 0xF);
+				};
+
+			append_hex_byte((component1 >> 24) & 0xFF);
+			append_hex_byte((component1 >> 16) & 0xFF);
+			append_hex_byte((component1 >>  8) & 0xFF);
+			append_hex_byte((component1 >>  0) & 0xFF);
+			*ptr++ = '-';
+			append_hex_byte((component2 >>  8) & 0xFF);
+			append_hex_byte((component2 >>  0) & 0xFF);
+			*ptr++ = '-';
+			append_hex_byte((component3 >>  8) & 0xFF);
+			append_hex_byte((component3 >>  0) & 0xFF);
+			*ptr++ = '-';
+			append_hex_byte(component45[0]);
+			append_hex_byte(component45[1]);
+			*ptr++ = '-';
+			append_hex_byte(component45[2]);
+			append_hex_byte(component45[3]);
+			append_hex_byte(component45[4]);
+			append_hex_byte(component45[5]);
+			append_hex_byte(component45[6]);
+			append_hex_byte(component45[7]);
+			*ptr = '\0';
+
+			BAN::String guid;
+			TRY(guid.append(buffer));
+			return BAN::move(guid);
+		}
 	};
 	static_assert(sizeof(GUID) == 16);
 

BAN/include/BAN/RefPtr.h

@@ -44,7 +44,7 @@ namespace BAN
 			uint32_t old = m_ref_count.fetch_sub(1);
 			ASSERT(old > 0);
 			if (old == 1)
-				delete (const T*)this;
+				delete static_cast<const T*>(this);
 		}
 
 	protected:

kernel/include/kernel/ACPI/AML/Event.h

@@ -0,0 +1,143 @@
+#pragma once
+
+#include <kernel/ACPI/AML/Bytes.h>
+#include <kernel/ACPI/AML/Integer.h>
+#include <kernel/ACPI/AML/NamedObject.h>
+#include <kernel/ACPI/AML/ParseContext.h>
+#include <kernel/ThreadBlocker.h>
+#include <kernel/Timer/Timer.h>
+
+namespace Kernel::ACPI::AML
+{
+
+	struct Event : public AML::NamedObject
+	{
+		BAN::Atomic<uint32_t> signal_count { 0 };
+		ThreadBlocker thread_blocker;
+
+		Event(NameSeg name)
+			: NamedObject(Node::Type::Event, name)
+		{}
+
+		static ParseResult parse(ParseContext& context)
+		{
+			ASSERT(context.aml_data.size() >= 2);
+			ASSERT(static_cast<AML::Byte>(context.aml_data[0]) == AML::Byte::ExtOpPrefix);
+
+			const auto ext_op = static_cast<AML::ExtOp>(context.aml_data[1]);
+			switch (ext_op)
+			{
+				case AML::ExtOp::EventOp:
+					return parse_event(context);
+				case AML::ExtOp::ResetOp:
+				case AML::ExtOp::SignalOp:
+				case AML::ExtOp::WaitOp:
+					break;
+				default:
+					ASSERT_NOT_REACHED();
+			}
+
+			context.aml_data = context.aml_data.slice(2);
+
+			auto event_result = parse_object(context);
+			if (!event_result.success())
+				return ParseResult::Failure;
+
+			auto general_node = event_result.node() ? event_result.node()->evaluate() : BAN::RefPtr<AML::Node>();
+			if (!general_node || general_node->type != Node::Type::Event)
+			{
+				AML_ERROR("Release, Wait or Signal does not name an event");
+				return ParseResult::Failure;
+			}
+
+			auto* event_node = static_cast<AML::Event*>(general_node.ptr());
+
+			if (ext_op == AML::ExtOp::WaitOp)
+			{
+				auto timeout_result = parse_object(context);
+				if (!timeout_result.success())
+					return ParseResult::Failure;
+
+				auto timeout = timeout_result.node() ? timeout_result.node()->as_integer() : BAN::RefPtr<AML::Integer>();
+				if (!timeout)
+				{
+					AML_ERROR("Wait timeout does not evaluate to integer");
+					return ParseResult::Failure;
+				}
+
+				const uint64_t start_ms = SystemTimer::get().ms_since_boot();
+				while (true)
+				{
+					auto expected = event_node->signal_count.load();
+					while (true)
+					{
+						if (expected == 0)
+							break;
+						if (event_node->signal_count.compare_exchange(expected, expected - 1))
+							return ParseResult(Integer::Constants::Zero);
+					}
+
+					if (timeout->value >= 0xFFFF)
+						event_node->thread_blocker.block_indefinite();
+					else
+					{
+						const uint64_t current_ms = SystemTimer::get().ms_since_boot();
+						if (current_ms >= start_ms + timeout->value)
+							return ParseResult(Integer::Constants::Ones);
+						event_node->thread_blocker.block_with_timeout_ms(start_ms + timeout->value - current_ms);
+					}
+				}
+
+				ASSERT_NOT_REACHED();
+			}
+
+			switch (ext_op)
+			{
+				case AML::ExtOp::ResetOp:
+					event_node->signal_count = 0;
+					break;
+				case AML::ExtOp::SignalOp:
+					event_node->signal_count++;
+					event_node->thread_blocker.unblock();
+					break;
+				default:
+					ASSERT_NOT_REACHED();
+			}
+
+			return ParseResult::Success;
+		}
+
+		virtual void debug_print(int indent) const override
+		{
+			AML_DEBUG_PRINT_INDENT(indent);
+			AML_DEBUG_PRINT("Event ");
+			name.debug_print();
+			AML_DEBUG_PRINT(" (Signals: {})", signal_count.load());
+		}
+
+	private:
+		static ParseResult parse_event(ParseContext& context)
+		{
+			ASSERT(context.aml_data.size() >= 2);
+			ASSERT(static_cast<AML::Byte>(context.aml_data[0]) == AML::Byte::ExtOpPrefix);
+			ASSERT(static_cast<AML::ExtOp>(context.aml_data[1]) == AML::ExtOp::EventOp);
+			context.aml_data = context.aml_data.slice(2);
+
+			auto name_string = NameString::parse(context.aml_data);
+			if (!name_string.has_value())
+				return ParseResult::Failure;
+
+			auto event = MUST(BAN::RefPtr<Event>::create(name_string->path.back()));
+			if (!Namespace::root_namespace()->add_named_object(context, name_string.value(), event))
+				return ParseResult::Success;
+
+#if AML_DEBUG_LEVEL >= 2
+			event->debug_print(0);
+			AML_DEBUG_PRINTLN("");
+#endif
+
+			return ParseResult::Success;
+		}
+	};
+
+}

kernel/include/kernel/ACPI/AML/Node.h

@@ -25,6 +25,7 @@ namespace Kernel::ACPI::AML
 			BufferField,
 			Debug,
 			Device,
+			Event,
 			FieldElement,
 			IndexFieldElement,
 			Integer,

kernel/include/kernel/Storage/Partition.h

@@ -25,6 +25,8 @@ namespace Kernel
 
 		virtual BAN::StringView name() const override { return m_name; }
 
+		BAN::StringView uuid() const { return m_guid_string; }
+
 	private:
 		Partition(BAN::RefPtr<BlockDevice>, const BAN::GUID&, const BAN::GUID&, uint64_t, uint64_t, uint64_t, const char*, uint32_t, BAN::StringView);
 
@@ -32,6 +34,7 @@ namespace Kernel
 		BAN::RefPtr<BlockDevice> m_device;
 		const BAN::GUID m_type;
 		const BAN::GUID m_guid;
+		const BAN::String m_guid_string;
 		const uint64_t m_first_block;
 		const uint64_t m_last_block;
 		const uint64_t m_attributes;

kernel/kernel/ACPI/AML/Node.cpp

@@ -3,6 +3,7 @@
 #include <kernel/ACPI/AML/Bytes.h>
 #include <kernel/ACPI/AML/Device.h>
 #include <kernel/ACPI/AML/Expression.h>
+#include <kernel/ACPI/AML/Event.h>
 #include <kernel/ACPI/AML/Field.h>
 #include <kernel/ACPI/AML/IfElse.h>
 #include <kernel/ACPI/AML/Index.h>
@@ -76,6 +77,11 @@ namespace Kernel::ACPI
 					return AML::OpRegion::parse(context);
 				case AML::ExtOp::DeviceOp:
 					return AML::Device::parse(context);
+				case AML::ExtOp::EventOp:
+				case AML::ExtOp::ResetOp:
+				case AML::ExtOp::SignalOp:
+				case AML::ExtOp::WaitOp:
+					return AML::Event::parse(context);
 				case AML::ExtOp::MutexOp:
 				case AML::ExtOp::AcquireOp:
 				case AML::ExtOp::ReleaseOp:

kernel/kernel/FS/DevFS/FileSystem.cpp

@@ -113,6 +113,8 @@ namespace Kernel
 		ASSERT(!device->name().contains('/'));
 		MUST(static_cast<TmpDirectoryInode*>(root_inode().ptr())->link_inode(*device, device->name()));
 		MUST(m_devices.push_back(device));
+
+		dprintln("Added device /dev/{}", device->name());
 	}
 
 	void DevFileSystem::remove_device(BAN::RefPtr<Device> device)
@@ -128,6 +130,8 @@ namespace Kernel
 				break;
 			}
 		}
+
+		dprintln("Removed device /dev/{}", device->name());
 	}
 
 	void DevFileSystem::add_inode(BAN::StringView path, BAN::RefPtr<TmpInode> inode)

kernel/kernel/FS/VirtualFileSystem.cpp

@@ -5,6 +5,8 @@
 #include <kernel/FS/TmpFS/FileSystem.h>
 #include <kernel/FS/VirtualFileSystem.h>
 #include <kernel/Lock/LockGuard.h>
+#include <kernel/Storage/Partition.h>
+
 #include <fcntl.h>
 
 namespace Kernel
@@ -17,13 +19,57 @@ namespace Kernel
 		ASSERT(!s_instance);
 		s_instance = MUST(BAN::RefPtr<VirtualFileSystem>::create());
 
-		ASSERT(root_path.size() >= 5 && root_path.substring(0, 5) == "/dev/"_sv);;
-		root_path = root_path.substring(5);
+		BAN::RefPtr<BlockDevice> root_device;
+		if (root_path.size() >= 5 && root_path.substring(0, 5) == "UUID="_sv)
+		{
+			auto uuid = root_path.substring(5);
+			if (uuid.size() != 36)
+				panic("Invalid UUID specified for root '{}'", uuid);
 
-		auto root_inode = MUST(DevFileSystem::get().root_inode()->find_inode(root_path));
-		if (!root_inode->mode().ifblk())
-			Kernel::panic("Specified root '/dev/{}' does not name a block device", root_path);
-		s_instance->m_root_fs = MUST(FileSystem::from_block_device(static_cast<BlockDevice*>(root_inode.ptr())));
+			BAN::RefPtr<Partition> root_partition;
+			DevFileSystem::get().for_each_inode(
+				[&root_partition, uuid](BAN::RefPtr<Inode> inode) -> BAN::Iteration
+				{
+					if (!inode->is_device())
+						return BAN::Iteration::Continue;
+					if (!static_cast<Device*>(inode.ptr())->is_partition())
+						return BAN::Iteration::Continue;
+					auto* partition = static_cast<Partition*>(inode.ptr());
+					dprintln("compare '{}' vs '{}'", partition->uuid(), uuid);
+					if (partition->uuid() != uuid)
+						return BAN::Iteration::Continue;
+					dprintln("FOUND");
+					root_partition = partition;
+					return BAN::Iteration::Break;
+				}
+			);
+			if (!root_partition)
+				panic("Could not find partition with UUID '{}'", uuid);
+			root_device = root_partition;
+		}
+		else if (root_path.size() >= 5 && root_path.substring(0, 5) == "/dev/"_sv)
+		{
+			auto device_name = root_path.substring(5);
+
+			auto device_result = DevFileSystem::get().root_inode()->find_inode(device_name);
+			if (device_result.is_error())
+				panic("Could not open root device '{}': {}", root_path, device_result.error());
+
+			auto device_inode = device_result.release_value();
+			if (!device_inode->mode().ifblk())
+				panic("Root inode '{}' is not an block device", root_path);
+
+			root_device = static_cast<BlockDevice*>(device_inode.ptr());
+		}
+		else
+		{
+			panic("Unknown root path format '{}' specified", root_path);
+		}
+
+		auto filesystem_result = FileSystem::from_block_device(root_device);
+		if (filesystem_result.is_error())
+			panic("Could not create filesystem from '{}': {}", root_path, filesystem_result.error());
+		s_instance->m_root_fs = filesystem_result.release_value();
 
 		Credentials root_creds { 0, 0, 0, 0 };
 		MUST(s_instance->mount(root_creds, &DevFileSystem::get(), "/dev"_sv));

kernel/kernel/Storage/Partition.cpp

@@ -18,6 +18,7 @@ namespace Kernel
 		, m_device(device)
 		, m_type(type)
 		, m_guid(guid)
+		, m_guid_string(MUST(guid.to_string()))
 		, m_first_block(first_block)
 		, m_last_block(last_block)
 		, m_attributes(attr)