Made it possible to build kernel modules for x86_64.

Added the necessary build flags for modules, and added a module (dpc)
to the floppy image for x86_64 builds for testing purposes. The module
gets loaded correctly and its code runs without issue. Only non-trivial
addition is the different method for generating kernel.so, this is
explained in the kernel Jamfile.

build/jam/BuildSetup

@@ -356,6 +356,7 @@ if $(HAIKU_GCC_VERSION[1]) >= 4 {
 
 HAIKU_KERNEL_PIC_CCFLAGS = -fno-pic ;
 HAIKU_KERNEL_PIC_LINKFLAGS = ;
+HAIKU_KERNEL_ADDON_LINKFLAGS = ;
 
 switch $(HAIKU_ARCH) {
 	case ppc :
@@ -389,13 +390,16 @@ switch $(HAIKU_ARCH) {
 	case x86_64 :
 	{
 		# Kernel lives in the top 2GB of the address space, use kernel code
-		# model. Also disable the red zone, which cannot be used in kernel
-		# code due to interrupts.
-		HAIKU_KERNEL_CCFLAGS += -mcmodel=kernel -mno-red-zone
-			-fno-omit-frame-pointer ;
-		HAIKU_KERNEL_C++FLAGS += -mcmodel=kernel -mno-red-zone
-			-fno-omit-frame-pointer ;
+		# model.
+		HAIKU_KERNEL_PIC_CCFLAGS += -mcmodel=kernel ;
+
+		# Disable the red zone, which cannot be used in kernel code due to
+		# interrupts, and always enable the frame pointer so stack traces are
+		# correct.
+		HAIKU_KERNEL_CCFLAGS += -mno-red-zone -fno-omit-frame-pointer ;
+		HAIKU_KERNEL_C++FLAGS += -mno-red-zone -fno-omit-frame-pointer ;
 		HAIKU_KERNEL_PIC_LINKFLAGS += -z max-page-size=0x1000 ;
+		HAIKU_KERNEL_ADDON_LINKFLAGS += -z max-page-size=0x1000 ;
 
 		# Bootloader is 32-bit.
 		HAIKU_BOOT_LINKFLAGS += -m elf_i386_haiku ;
@@ -984,7 +988,7 @@ if $(TARGET_PLATFORM) != haiku {
 local buildVars =
 	ARCH CPU GCC_VERSION KERNEL_ARCH
 
-	AR CC C++ LD OBJCOPY RANLIB
+	AR CC C++ LD OBJCOPY RANLIB ELFEDIT
 
 	INCLUDES_SEPARATOR LOCAL_INCLUDES_OPTION SYSTEM_INCLUDES_OPTION
 
@@ -993,7 +997,7 @@ local buildVars =
 	KERNEL_DEFINES
 
 	KERNEL_CCFLAGS KERNEL_C++FLAGS
-	KERNEL_PIC_CCFLAGS KERNEL_PIC_LINKFLAGS
+	KERNEL_PIC_CCFLAGS KERNEL_PIC_LINKFLAGS KERNEL_ADDON_LINKFLAGS
 	BOOT_CCFLAGS BOOT_C++FLAGS BOOT_LINKFLAGS
 	WARNING_CCFLAGS WARNING_C++FLAGS
 

build/jam/FloppyBootImage

@@ -52,7 +52,10 @@ SYSTEM_ADD_ONS_BUS_MANAGERS = $(X86_ONLY)acpi $(ATA_ONLY)ata config_manager dpc
 SYSTEM_ADD_ONS_FILE_SYSTEMS = bfs iso9660 attribute_overlay write_overlay ;
 
 
-if $(TARGET_ARCH) != x86_64 {
+if $(TARGET_ARCH) = x86_64 {
+	AddFilesToFloppyBootArchive system add-ons kernel bus_managers
+		: dpc ;
+} else {
 	# modules
 	AddFilesToFloppyBootArchive system add-ons kernel bus_managers
 		: $(SYSTEM_ADD_ONS_BUS_MANAGERS) ;
@@ -121,7 +124,11 @@ if $(NET_BOOT) = 1 {
 }
 
 # boot module links
-if $(TARGET_ARCH) != x86_64 {
+if $(TARGET_ARCH) = x86_64 {
+	AddBootModuleSymlinksToFloppyBootArchive
+		dpc
+	;
+} else {
 	AddBootModuleSymlinksToFloppyBootArchive
 		$(SYSTEM_ADD_ONS_BUS_MANAGERS)
 		$(PPC_ONLY)openpic

build/jam/KernelRules

@@ -77,6 +77,24 @@ actions KernelLd bind VERSION_SCRIPT
 		--version-script=$(VERSION_SCRIPT)
 }
 
+rule KernelSo target : source
+{
+	# KernelSo <target> : <source>
+
+	Depends $(target) : <build>copyattr $(source) ;
+
+	MakeLocateDebug $(1) ;
+	KernelSo1 $(target) : <build>copyattr $(source) ;
+}
+
+actions KernelSo1
+{
+	$(HOST_ADD_BUILD_COMPATIBILITY_LIB_DIR)
+
+	$(2[1]) --data $(2[2]) $(1) &&
+	$(HAIKU_ELFEDIT) --output-type dyn $(1)
+}
+
 rule KernelAddon
 {
 	# KernelAddon <name> : <sources> : <static-libraries> : <res> ;
@@ -117,7 +135,7 @@ rule KernelAddon
 	# compile and link
 	SetupKernel $(sources) : $(TARGET_KERNEL_PIC_FLAGS) : false ;
 	local linkFlags = -nostdlib -Xlinker --no-undefined
-		-Xlinker -soname=\"$(target:G=)\" ;
+		-Xlinker -soname=\"$(target:G=)\" $(TARGET_KERNEL_ADDON_LINKFLAGS) ;
 	LINKFLAGS on $(target) = [ on $(target) return $(LINKFLAGS) ] $(linkFlags) ;
 	Main $(target) : $(sources) ;
 	LinkAgainst $(target) : $(libs) $(kernel) ;