Commit 433de739 authored by H. Peter Anvin's avatar H. Peter Anvin

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 scripts/x86-relocs.c so it will
be compiled before building the arch/x86 tree.
Signed-off-by: default avatarH. Peter Anvin <>
Link: default avatarJarkko Sakkinen <>
Signed-off-by: default avatarH. Peter Anvin <>
parent d48b97b4
......@@ -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
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
CMD_RELOCS = scripts/x86-relocs
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux FORCE
$(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin
......@@ -9,3 +9,4 @@ unifdef
......@@ -8,11 +8,14 @@
# conmakehash: Create arrays for initializing the kernel console tables
# docproc: Used in Documentation/DocBook
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-$(CONFIG_KALLSYMS) += kallsyms
hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash
hostprogs-$(CONFIG_IKCONFIG) += bin2c
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_X86) += x86-relocs
always := $(hostprogs-y) $(hostprogs-m)
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