fix(build): remove program headers from first loadable segment

Program headers should not be loaded into kernel as there is no use for
them. Previously starting kernel at start of memory region required
explicit linker script.

JIRA: RTOS-910

Author: Hubert Badocha

Makefile

@@ -53,14 +53,22 @@ include log/Makefile
 DEPS := $(patsubst %.o, %.c.d, $(OBJS))
 -include $(DEPS)
 
-$(PREFIX_PROG)phoenix-$(TARGET_FAMILY)-$(TARGET_SUBFAMILY).elf: $(OBJS)
+
+# By default ld adds program headers to first LOAD segment.
+# However, in kernel headers are not used and it is expected that kernel address space starts at _start.
+# This target creates linker script that do not add program headers into the first loadable segment.
+# 1) Get internal linker script with prefix and suffix containing noise.
+# 2) Match only internal linker script which is between two lines of =
+# 3) Remove those lines
+# 4) Remove "+ SIZEOF_HEADERS", which causes inclusion of program headers.
+$(PREFIX_O)$(TARGET_FAMILY)-$(TARGET_SUBFAMILY).ldt:
+	$(SIL)$(LD) $(LDFLAGS_PREFIX)--verbose 2>/dev/null | sed -n '/^==*$$/,/^==*$$/p' | sed '1,1d; $$d' | sed s/"\s*+\s*SIZEOF_HEADERS"// > "$@"
+
+
+$(PREFIX_PROG)phoenix-$(TARGET_FAMILY)-$(TARGET_SUBFAMILY).elf: $(OBJS) $(PREFIX_O)$(TARGET_FAMILY)-$(TARGET_SUBFAMILY).ldt
 	@mkdir -p $(@D)
 	@(printf "LD  %-24s\n" "$(@F)");
-ifeq ($(TARGET_FAMILY),sparcv8leon3)
-	$(SIL)$(LD) $(CFLAGS) $(LDFLAGS) -nostdlib -e _start -Wl,--section-start,.init=$(VADDR_KERNEL_INIT) -o $@ $(OBJS) -lgcc -T ld/sparcv8leon3.ld
-else
-	$(SIL)$(LD) $(CFLAGS) $(LDFLAGS) -nostdlib -e _start -Wl,--section-start,.init=$(VADDR_KERNEL_INIT) -o $@ $(OBJS) -lgcc
-endif
+	$(SIL)$(LD) $(CFLAGS) $(LDFLAGS) -nostdlib -e _start -Wl,--section-start,.init=$(VADDR_KERNEL_INIT) -o $@ $(OBJS) -lgcc -T $(PREFIX_O)$(TARGET_FAMILY)-$(TARGET_SUBFAMILY).ldt
 
 install-headers: $(EXTERNAL_HEADERS)
 	@printf "Installing kernel headers\n"