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x86, realmode: 16-bit real-mode code support for relocs tool

A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.

In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.

16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.

The relocs tool is moved to arch/x86/tools/relocs.c, and added new
target archscripts that can be used to build scripts needed building
an architecture.  be compiled before building the arch/x86 tree.

[ hpa: accelerating this because it detects invalid absolute
  relocations, a serious bug in binutils which currently
  produces bad kernels. ]

Signed-off-by: H. Peter Anvin <>
Signed-off-by: Jarkko Sakkinen <>
Signed-off-by: H. Peter Anvin <>
Cc: <>
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1 parent 36be505 commit 6520fe5564acf07ade7b18a1272db1184835c487 H. Peter Anvin committed May 8, 2012
@@ -442,7 +442,7 @@ asm-generic:
no-dot-config-targets := clean mrproper distclean \
cscope gtags TAGS tags help %docs check% coccicheck \
- include/linux/version.h headers_% archheaders \
+ include/linux/version.h headers_% archheaders archscripts \
kernelversion %src-pkg
config-targets := 0
@@ -979,7 +979,7 @@ prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
-archprepare: archheaders prepare1 scripts_basic
+archprepare: archheaders archscripts prepare1 scripts_basic
prepare0: archprepare FORCE
$(Q)$(MAKE) $(build)=.
@@ -1049,8 +1049,11 @@ hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)
PHONY += archheaders
+PHONY += archscripts
PHONY += __headers
-__headers: include/linux/version.h scripts_basic asm-generic archheaders FORCE
+__headers: include/linux/version.h scripts_basic asm-generic archheaders archscripts FORCE
$(Q)$(MAKE) $(build)=scripts build_unifdef
PHONY += headers_install_all
@@ -134,6 +134,9 @@ KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
KBUILD_CFLAGS += $(mflags-y)
KBUILD_AFLAGS += $(mflags-y)
+ $(Q)$(MAKE) $(build)=arch/x86/tools relocs
# Syscall table generation
@@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
+targets += vmlinux.bin.all vmlinux.relocs
-targets += vmlinux.bin.all vmlinux.relocs relocs
-hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs
+CMD_RELOCS = arch/x86/tools/relocs
quiet_cmd_relocs = RELOCS $@
- cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
-$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
+ cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+$(obj)/vmlinux.relocs: vmlinux FORCE
$(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin
@@ -0,0 +1 @@
@@ -36,3 +36,7 @@ HOSTCFLAGS_insn_sanity.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x
$(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
$(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
+HOST_EXTRACFLAGS += -I$(srctree)/tools/include
+hostprogs-y += relocs
+relocs: $(obj)/relocs
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