Changes to kernel_args to make it identical for x86 and x86_64.

* Added a FixedWidthPointer template class which uses 64-bit storage to hold
  a pointer. This is used in place of raw pointers in kernel_args.
* Added __attribute__((packed)) to kernel_args and all structures contained
  within it. This is necessary due to different alignment behaviour for
  32-bit and 64-bit compilation with GCC.
* With these changes, kernel_args will now come out the same size for both
  the x86_64 kernel and the loader, excluding the preloaded_image structure
  which has not yet been changed.
* Tested both an x86 GCC2 and GCC4 build, no problems caused by these changes.

headers/private/kernel/arch/x86/arch_kernel_args.h

@@ -9,6 +9,10 @@
 #	error This file is included from <boot/kernel_args.h> only
 #endif
 
+
+#include <util/FixedWidthPointer.h>
+
+
 #define MAX_BOOT_PTABLES 4
 
 #define _PACKED __attribute__((packed))
@@ -34,14 +38,13 @@ typedef struct {
 	// smp stuff
 	uint32	apic_time_cv_factor; // apic ticks per second
 	uint32	apic_phys;
-	uint32	*apic;
+	FixedWidthPointer<void> apic;
 	uint32	ioapic_phys;
-	uint32	*ioapic;
 	uint32	cpu_apic_id[MAX_BOOT_CPUS];
 	uint32	cpu_apic_version[MAX_BOOT_CPUS];
 	// hpet stuff
 	uint32	hpet_phys;
-	uint32	*hpet;
-} arch_kernel_args;
+	FixedWidthPointer<void> hpet;
+} _PACKED arch_kernel_args;
 
 #endif	/* KERNEL_ARCH_x86_KERNEL_ARGS_H */

headers/private/kernel/boot/addr_range.h

@@ -13,13 +13,13 @@
 typedef struct addr_range {
 	uint64 start;
 	uint64 size;
-} addr_range;
+} _PACKED addr_range;
 
 
 typedef struct phys_addr_range {
 	phys_addr_t	start;
 	phys_size_t	size;
-} phys_addr_range;
+} _PACKED phys_addr_range;
 
 
 #ifdef __cplusplus

headers/private/kernel/boot/driver_settings.h

@@ -6,11 +6,12 @@
 #define KERNEL_BOOT_DRIVER_SETTINGS_H
 
 
+#include <util/FixedWidthPointer.h>
 #include <util/list.h>
 
 
 struct driver_settings_file {
-	struct driver_settings_file *next;
+	FixedWidthPointer<struct driver_settings_file> next;
 	char	name[B_OS_NAME_LENGTH];
 	char	*buffer;
 	size_t	size;

headers/private/kernel/boot/elf.h

@@ -9,10 +9,11 @@
 #include <boot/addr_range.h>
 #include <sys/stat.h>
 #include <elf_priv.h>
+#include <util/FixedWidthPointer.h>
 
 
 struct preloaded_image {
-	struct preloaded_image *next;
+	FixedWidthPointer<struct preloaded_image> next;
 	char		*name;
 	elf_region	text_region;
 	elf_region	data_region;
@@ -37,7 +38,7 @@ struct preloaded_image {
 		// the ID field will be filled out in the kernel
 	bool		is_module;
 		// set by the module initialization code
-};
+} _PACKED;
 
 #ifdef __cplusplus
 extern "C" {

headers/private/kernel/boot/kernel_args.h

@@ -18,6 +18,9 @@
 #include <platform_kernel_args.h>
 #include <arch_kernel_args.h>
 
+#include <util/FixedWidthPointer.h>
+
+
 #define CURRENT_KERNEL_ARGS_VERSION	1
 #define MAX_KERNEL_ARGS_RANGE		20
 
@@ -42,7 +45,7 @@ typedef struct kernel_args {
 	uint32		version;
 
 	struct preloaded_image kernel_image;
-	struct preloaded_image *preloaded_images;
+	FixedWidthPointer<struct preloaded_image> preloaded_images;
 
 	uint32			num_physical_memory_ranges;
 	phys_addr_range	physical_memory_range[MAX_PHYSICAL_MEMORY_RANGE];
@@ -58,10 +61,10 @@ typedef struct kernel_args {
 	addr_range	cpu_kstack[MAX_BOOT_CPUS];
 
 	// boot volume KMessage data
-	uint64		boot_volume;
+	FixedWidthPointer<void> boot_volume;
 	int32		boot_volume_size;
 
-	struct driver_settings_file *driver_settings;
+	FixedWidthPointer<struct driver_settings_file> driver_settings;
 
 	struct {
 		phys_addr_range	physical_buffer;
@@ -72,12 +75,12 @@ typedef struct kernel_args {
 		bool	enabled;
 	} frame_buffer;
 
-	void		*vesa_modes;
+	FixedWidthPointer<void> vesa_modes;
 	uint16		vesa_modes_size;
 	uint8		vesa_capabilities;
-	void		*edid_info;
+	FixedWidthPointer<void> edid_info;
 
-	void		*debug_output;
+	FixedWidthPointer<void> debug_output;
 	uint32		debug_size;
 	bool		keep_debug_output_buffer;
 
@@ -85,8 +88,8 @@ typedef struct kernel_args {
 	arch_kernel_args arch_args;
 
 	// bootsplash data
-	uint8 		*boot_splash;
+	FixedWidthPointer<uint8> boot_splash;
 
-} kernel_args;
+} _PACKED kernel_args;
 
 #endif	/* KERNEL_BOOT_KERNEL_ARGS_H */

headers/private/kernel/boot/platform/bios_ia32/platform_kernel_args.h

@@ -12,6 +12,7 @@
 
 #include <arch/x86/apm.h>
 #include <bios_drive.h>
+#include <util/FixedWidthPointer.h>
 
 
 // must match SMP_MAX_CPUS in arch_smp.h
@@ -25,9 +26,10 @@
 typedef struct {
 	uint16		serial_base_ports[MAX_SERIAL_PORTS];
 
-	bios_drive	*drives;	// this does not contain the boot drive
+	FixedWidthPointer<bios_drive> drives;
+		// this does not contain the boot drive
 
 	apm_info	apm;
-} platform_kernel_args;
+} _PACKED platform_kernel_args;
 
 #endif	/* KERNEL_BOOT_PLATFORM_BIOS_IA32_KERNEL_ARGS_H */

headers/private/kernel/util/FixedWidthPointer.h

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2012, Alex Smith, alex@alex-smith.me.uk.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef KERNEL_UTIL_FIXED_WIDTH_POINTER_H
+#define KERNEL_UTIL_FIXED_WIDTH_POINTER_H
+
+
+#include <SupportDefs.h>
+
+
+/*!
+	\class FixedWidthPointer
+	\brief Pointer class with fixed size (64-bit) storage.
+
+	This class is a pointer-like class that uses a fixed size 64-bit storage.
+	This is used to make kernel_args compatible (i.e. the same size) for both
+	32-bit and 64-bit kernels.
+*/
+template<typename Type>
+class FixedWidthPointer {
+public:
+	operator Type*() const
+	{
+		return (Type *)(addr_t)fValue;
+	}
+
+	operator addr_t() const
+	{
+		return (addr_t)fValue;
+	}
+
+	Type &operator*() const
+	{
+		return *(Type *)*this;
+	}
+
+	Type *operator->() const
+	{
+		return *this;
+	}
+
+	FixedWidthPointer &operator=(const FixedWidthPointer &p)
+	{
+		fValue = p.fValue;
+		return *this;
+	}
+
+	FixedWidthPointer &operator=(Type *p)
+	{
+		fValue = (addr_t)p;
+		return *this;
+	}
+
+	/*!
+		Get the 64-bit pointer value.
+		\return Pointer address.
+	*/
+	uint64 Get() const
+	{
+		return fValue;
+	}
+
+	/*!
+		Set the 64-bit pointer value.
+		\param addr New address for the pointer.
+	*/
+	void SetTo(uint64 addr)
+	{
+		fValue = addr;
+	}
+private:
+	uint64 fValue;
+} _PACKED;
+
+
+// Specialization for void pointers, can be converted to another pointer type.
+template<>
+class FixedWidthPointer<void> {
+public:
+	operator void*() const
+	{
+		return (void *)(addr_t)fValue;
+	}
+
+	template<typename OtherType>
+	operator OtherType*() const
+	{
+		return (OtherType *)(addr_t)fValue;
+	}
+
+	operator addr_t() const
+	{
+		return (addr_t)fValue;
+	}
+
+	FixedWidthPointer &operator=(const FixedWidthPointer &p)
+	{
+		fValue = p.fValue;
+		return *this;
+	}
+
+	FixedWidthPointer &operator=(void *p)
+	{
+		fValue = (addr_t)p;
+		return *this;
+	}
+
+	uint64 Get() const
+	{
+		return fValue;
+	}
+
+	void SetTo(uint64 addr)
+	{
+		fValue = addr;
+	}
+private:
+	uint64 fValue;
+} _PACKED;
+
+
+#endif	/* KERNEL_UTIL_FIXED_WIDTH_POINTER_H */

src/system/boot/loader/main.cpp

@@ -128,7 +128,7 @@ main(stage2_args *args)
 
 			buffer = (void*)(((addr_t)buffer + 3) & ~(addr_t)0x3);
 			memcpy(buffer, gBootVolume.Buffer(), gBootVolume.ContentSize());
-			gKernelArgs.boot_volume = (addr_t)buffer;
+			gKernelArgs.boot_volume = buffer;
 			gKernelArgs.boot_volume_size = gBootVolume.ContentSize();
 
 			// ToDo: cleanup, heap_release() etc.

src/system/boot/platform/bios_ia32/debug.cpp

@@ -162,7 +162,7 @@ debug_cleanup(void)
 
 	if (!gKernelArgs.keep_debug_output_buffer) {
 		gKernelArgs.debug_output = kernel_args_malloc(sBufferPosition);
-		if (gKernelArgs.debug_output != NULL) {
+		if (gKernelArgs.debug_output) {
 			memcpy(gKernelArgs.debug_output, sBuffer, sBufferPosition);
 			gKernelArgs.debug_size = sBufferPosition;
 		}

src/system/boot/platform/bios_ia32/hpet.cpp

@@ -50,6 +50,6 @@ hpet_init(void)
 
 	TRACE(("hpet_init: found HPET at %x.\n", hpet->hpet_address.address));
 	gKernelArgs.arch_args.hpet_phys = hpet->hpet_address.address;
-	gKernelArgs.arch_args.hpet = (uint32 *)mmu_map_physical_memory(
+	gKernelArgs.arch_args.hpet = (void *)mmu_map_physical_memory(
 		gKernelArgs.arch_args.hpet_phys, B_PAGE_SIZE, kDefaultPageFlags);
 }

src/system/boot/platform/bios_ia32/smp.cpp

@@ -60,21 +60,21 @@ static int smp_get_current_cpu(void);
 static uint32
 apic_read(uint32 offset)
 {
-	return *(volatile uint32 *)((uint32)gKernelArgs.arch_args.apic + offset);
+	return *(volatile uint32 *)((addr_t)gKernelArgs.arch_args.apic + offset);
 }
 
 
 static void
 apic_write(uint32 offset, uint32 data)
 {
-	*(volatile uint32 *)((uint32)gKernelArgs.arch_args.apic + offset) = data;
+	*(volatile uint32 *)((addr_t)gKernelArgs.arch_args.apic + offset) = data;
 }
 
 
 static int
 smp_get_current_cpu(void)
 {
-	if (gKernelArgs.arch_args.apic == NULL)
+	if (!gKernelArgs.arch_args.apic)
 		return 0;
 
 	uint8 apicID = apic_read(APIC_ID) >> 24;
@@ -451,10 +451,10 @@ smp_init_other_cpus(void)
 		(void *)gKernelArgs.arch_args.ioapic_phys));
 
 	// map in the apic
-	gKernelArgs.arch_args.apic = (uint32 *)mmu_map_physical_memory(
+	gKernelArgs.arch_args.apic = (void *)mmu_map_physical_memory(
 		gKernelArgs.arch_args.apic_phys, B_PAGE_SIZE, kDefaultPageFlags);
 
-	TRACE(("smp: apic (mapped) = %p\n", gKernelArgs.arch_args.apic));
+	TRACE(("smp: apic (mapped) = %p\n", (void *)gKernelArgs.arch_args.apic));
 
 	// calculate how fast the apic timer is
 	calculate_apic_timer_conversion_factor();

src/system/boot/platform/bios_ia32/video.cpp

@@ -957,7 +957,7 @@ platform_init_video(void)
 		}
 
 		gKernelArgs.edid_info = kernel_args_malloc(sizeof(edid1_info));
-		if (gKernelArgs.edid_info != NULL)
+		if (gKernelArgs.edid_info)
 			memcpy(gKernelArgs.edid_info, &info, sizeof(edid1_info));
 	}
 

src/system/boot/platform/generic/video_splash.cpp

@@ -146,12 +146,12 @@ video_display_splash(addr_t frameBuffer)
 			// pointer into the lower half of the icons image data
 			gKernelArgs.boot_splash
 				= (uint8*)kernel_args_malloc(uncompressedSize);
-			if (gKernelArgs.boot_splash == NULL)
+			if (!gKernelArgs.boot_splash)
 				return B_NO_MEMORY;
 			uncompress(kSplashIcons8BitCompressedImage,
 				sizeof(kSplashIcons8BitCompressedImage),
 				gKernelArgs.boot_splash, uncompressedSize);
-			lowerHalfIconImage = gKernelArgs.boot_splash
+			lowerHalfIconImage = (uint8 *)gKernelArgs.boot_splash
 				+ (kSplashIconsWidth * iconsHalfHeight);
 		break;
 		default:	// 24bits is assumed here
@@ -159,12 +159,12 @@ video_display_splash(addr_t frameBuffer)
 			// pointer into the lower half of the icons image data
 			gKernelArgs.boot_splash
 				= (uint8*)kernel_args_malloc(uncompressedSize);
-			if (gKernelArgs.boot_splash == NULL)
+			if (!gKernelArgs.boot_splash)
 				return B_NO_MEMORY;
 			uncompress(kSplashIcons24BitCompressedImage,
 				sizeof(kSplashIcons24BitCompressedImage),
 				gKernelArgs.boot_splash, uncompressedSize);
-			lowerHalfIconImage = gKernelArgs.boot_splash
+			lowerHalfIconImage = (uint8 *)gKernelArgs.boot_splash
 				+ (kSplashIconsWidth * iconsHalfHeight) * 3;
 		break;
 	}

src/system/boot/platform/openfirmware/video.cpp

@@ -126,7 +126,7 @@ platform_init_video(void)
 		edid_dump(&info);
 #endif
 		gKernelArgs.edid_info = kernel_args_malloc(sizeof(edid1_info));
-		if (gKernelArgs.edid_info != NULL)
+		if (gKernelArgs.edid_info)
 			memcpy(gKernelArgs.edid_info, &info, sizeof(edid1_info));
 	}
 

src/system/boot/platform/u-boot/serial.cpp

@@ -83,7 +83,7 @@ serial_cleanup(void)
 		return;
 
 	gKernelArgs.debug_output = kernel_args_malloc(sBufferPosition);
-	if (gKernelArgs.debug_output != NULL) {
+	if (gKernelArgs.debug_output) {
 		memcpy(gKernelArgs.debug_output, sBuffer, sBufferPosition);
 		gKernelArgs.debug_size = sBufferPosition;
 	}

src/system/kernel/arch/x86/apic.cpp

@@ -68,7 +68,7 @@ apic_disable_local_ints()
 status_t
 apic_init(kernel_args *args)
 {
-	if (args->arch_args.apic == NULL)
+	if (!args->arch_args.apic)
 		return B_NO_INIT;
 
 	sLocalAPIC = args->arch_args.apic;

src/system/kernel/arch/x86/ioapic.cpp

@@ -650,7 +650,7 @@ ioapic_init(kernel_args* args)
 		&ioapic_end_of_interrupt
 	};
 
-	if (args->arch_args.apic == NULL)
+	if (!args->arch_args.apic)
 		return;
 
 	if (args->arch_args.ioapic_phys == 0) {

src/system/kernel/arch/x86/timers/x86_hpet.cpp

@@ -217,7 +217,7 @@ hpet_init(struct kernel_args *args)
 	/* hpet_acpi_probe() through a similar "scan spots" table
 	   to that of smp.cpp.
 	   Seems to be the most elegant solution right now. */
-	if (args->arch_args.hpet == NULL)
+	if (!args->arch_args.hpet)
 		return B_ERROR;
 
 	if (sHPETRegs == NULL) {

src/system/kernel/debug/debug.cpp

@@ -1401,7 +1401,7 @@ syslog_init_post_vm(struct kernel_args* args)
 	sSyslogMessage->ident[0] = '\0';
 	//strcpy(sSyslogMessage->ident, "KERNEL");
 
-	if (args->debug_output != NULL)
+	if (args->debug_output)
 		syslog_write((const char*)args->debug_output, args->debug_size, false);
 
 	char revisionBuffer[64];
@@ -1431,7 +1431,7 @@ err1:
 static status_t
 syslog_init(struct kernel_args* args)
 {
-	if (!args->keep_debug_output_buffer || args->debug_output == NULL)
+	if (!args->keep_debug_output_buffer || !args->debug_output)
 		return B_OK;
 
 	sSyslogBuffer = create_ring_buffer_etc(args->debug_output, args->debug_size,

src/system/kernel/debug/frame_buffer_console.cpp

@@ -442,7 +442,7 @@ frame_buffer_console_init(kernel_args* args)
 		add_boot_item(VESA_MODES_BOOT_INFO, sVesaModes, args->vesa_modes_size);
 	}
 
-	if (args->edid_info != NULL) {
+	if (args->edid_info) {
 		edid1_info* info = (edid1_info*)malloc(sizeof(edid1_info));
 		if (info != NULL) {
 			memcpy(info, args->edid_info, sizeof(edid1_info));

src/system/kernel/fs/vfs_boot.cpp

@@ -325,7 +325,7 @@ static status_t
 get_boot_partitions(kernel_args* args, PartitionStack& partitions)
 {
 	KMessage bootVolume;
-	bootVolume.SetTo((void *)(addr_t)args->boot_volume, args->boot_volume_size);
+	bootVolume.SetTo(args->boot_volume, args->boot_volume_size);
 
 	dprintf("get_boot_partitions(): boot volume message:\n");
 	bootVolume.Dump(&dprintf);