Kernel: Parse RSDP from multiboot headers if exists

kernel/include/kernel/BootInfo.h

@@ -3,6 +3,7 @@
 #include <BAN/String.h>
 #include <BAN/StringView.h>
 #include <BAN/Vector.h>
+#include <kernel/RSDP.h>
 
 namespace Kernel
 {
@@ -34,7 +35,8 @@ namespace Kernel
 	struct BootInfo
 	{
 		BAN::String					command_line;
-		FramebufferInfo				framebuffer;
+		FramebufferInfo				framebuffer			{};
+		RSDP						rsdp				{};
 		BAN::Vector<MemoryMapEntry>	memory_map_entries;
 	};
 

kernel/include/kernel/RSDP.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace Kernel
+{
+
+	struct RSDP
+	{
+		uint8_t signature[8];
+		uint8_t checksum;
+		uint8_t oemid[6];
+		uint8_t revision;
+		uint32_t rsdt_address;
+
+		// only in revision >= 2
+		uint32_t length;
+		uint64_t xsdt_address;
+		uint8_t extended_checksum;
+		uint8_t reserved[3];
+	};
+
+}

kernel/kernel/ACPI.cpp

@@ -1,6 +1,7 @@
 #include <BAN/ScopeGuard.h>
 #include <BAN/StringView.h>
 #include <kernel/ACPI.h>
+#include <kernel/BootInfo.h>
 #include <kernel/Memory/PageTable.h>
 
 #include <lai/core.h>
@@ -11,21 +12,6 @@
 namespace Kernel
 {
 
-	struct RSDP
-	{
-		uint8_t signature[8];
-		uint8_t checksum;
-		uint8_t oemid[6];
-		uint8_t revision;
-		uint32_t rsdt_address;
-
-		// only in revision >= 2
-		uint32_t length;
-		uint64_t xsdt_address;
-		uint8_t extended_checksum;
-		uint8_t reserved[3];
-	};
-
 	struct RSDT : public ACPI::SDTHeader
 	{
 		uint32_t entries[];
@@ -84,19 +70,13 @@ namespace Kernel
 
 	static const RSDP* locate_rsdp()
 	{
-		// FIXME: add this back
+		if (g_boot_info.rsdp.length)
-#if 0
+			return &g_boot_info.rsdp;
-		// Check the multiboot headers
-		if (auto* rsdp_new = (multiboot2_rsdp_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_NEW_RSDP))
-			return (const RSDP*)rsdp_new->data;
-		if (auto* rsdp_old = (multiboot2_rsdp_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_OLD_RSDP))
-			return (const RSDP*)rsdp_old->data;
-#endif
 
 		// Look in main BIOS area below 1 MB
 		for (uintptr_t addr = P2V(0x000E0000); addr < P2V(0x000FFFFF); addr += 16)
 			if (is_rsdp(addr))
-				return (const RSDP*)addr;
+				return reinterpret_cast<const RSDP*>(addr);
 		return nullptr;
 	}
 

kernel/kernel/BootInfo.cpp

@@ -7,7 +7,7 @@ namespace Kernel
 
 	BootInfo g_boot_info;
 
-	void parse_boot_info_multiboot2(uint32_t info)
+	static void parse_boot_info_multiboot2(uint32_t info)
 	{
 		const auto& multiboot2_info = *reinterpret_cast<const multiboot2_info_t*>(info);
 
@@ -15,12 +15,12 @@ namespace Kernel
 		{
 			if (tag->type == MULTIBOOT2_TAG_CMDLINE)
 			{
-				const auto& command_line_tag = *reinterpret_cast<const multiboot2_cmdline_tag_t*>(tag);
+				const auto& command_line_tag = *static_cast<const multiboot2_cmdline_tag_t*>(tag);
 				MUST(g_boot_info.command_line.append(command_line_tag.cmdline));
 			}
 			else if (tag->type == MULTIBOOT2_TAG_FRAMEBUFFER)
 			{
-				const auto& framebuffer_tag = *reinterpret_cast<const multiboot2_framebuffer_tag_t*>(tag);
+				const auto& framebuffer_tag = *static_cast<const multiboot2_framebuffer_tag_t*>(tag);
 				g_boot_info.framebuffer.address	= framebuffer_tag.framebuffer_addr;
 				g_boot_info.framebuffer.pitch	= framebuffer_tag.framebuffer_pitch;
 				g_boot_info.framebuffer.width	= framebuffer_tag.framebuffer_width;
@@ -33,7 +33,7 @@ namespace Kernel
 			}
 			else if (tag->type == MULTIBOOT2_TAG_MMAP)
 			{
-				const auto& mmap_tag = *reinterpret_cast<const multiboot2_mmap_tag_t*>(tag);
+				const auto& mmap_tag = *static_cast<const multiboot2_mmap_tag_t*>(tag);
 
 				const size_t entry_count = (mmap_tag.size - sizeof(multiboot2_mmap_tag_t)) / mmap_tag.entry_size;
 
@@ -52,19 +52,32 @@ namespace Kernel
 					g_boot_info.memory_map_entries[i].type		= mmap_entry.type;
 				}
 			}
+			else if (tag->type == MULTIBOOT2_TAG_OLD_RSDP)
+			{
+				if (g_boot_info.rsdp.length == 0)
+				{
+					memcpy(&g_boot_info.rsdp, static_cast<const multiboot2_rsdp_tag_t*>(tag)->data, 20);
+					g_boot_info.rsdp.length = 20;
+				}
+			}
+			else if (tag->type == MULTIBOOT2_TAG_NEW_RSDP)
+			{
+				const auto& rsdp = *reinterpret_cast<const RSDP*>(static_cast<const multiboot2_rsdp_tag_t*>(tag)->data);
+				memcpy(&g_boot_info.rsdp, &rsdp, BAN::Math::min<uint32_t>(rsdp.length, sizeof(g_boot_info.rsdp)));
+			}
 		}
 	}
 
-	BAN::StringView get_early_boot_command_line_multiboot2(uint32_t info)
+	static BAN::StringView get_early_boot_command_line_multiboot2(uint32_t info)
 	{
 		const auto& multiboot2_info = *reinterpret_cast<const multiboot2_info_t*>(info);
 		for (const auto* tag = multiboot2_info.tags; tag->type != MULTIBOOT2_TAG_END; tag = tag->next())
 			if (tag->type == MULTIBOOT2_TAG_CMDLINE)
-				return reinterpret_cast<const multiboot2_cmdline_tag_t*>(tag)->cmdline;
+				return static_cast<const multiboot2_cmdline_tag_t*>(tag)->cmdline;
 		return {};
 	}
 
-	void parse_boot_info_banan_bootloader(uint32_t info)
+	static void parse_boot_info_banan_bootloader(uint32_t info)
 	{
 		const auto& banan_bootloader_info = *reinterpret_cast<const BananBootloaderInfo*>(info);
 
@@ -93,7 +106,7 @@ namespace Kernel
 		}
 	}
 
-	BAN::StringView get_early_boot_command_line_banan_bootloader(uint32_t info)
+	static BAN::StringView get_early_boot_command_line_banan_bootloader(uint32_t info)
 	{
 		const auto& banan_bootloader_info = *reinterpret_cast<const BananBootloaderInfo*>(info);
 		return reinterpret_cast<const char*>(banan_bootloader_info.command_line_addr);