linux/arch/arm/boot/Makefile
Nicolas Pitre ca8b5d97d6 ARM: XIP kernel: store .data compressed in ROM
The .data segment stored in ROM is only copied to RAM once at boot time
and never referenced afterwards. This is arguably a suboptimal usage of
ROM resources.

This patch allows for compressing the .data segment before storing it
into ROM and decompressing it to RAM rather than simply copying it,
saving on precious ROM space.

Because global data is not available yet (obviously) we must allocate
decompressor workspace memory on the stack. The .bss area is used as a
stack area for that purpose before it is cleared. The required stack
frame is 9568 bytes for __inflate_kernel_data() alone, so make sure
the .bss is large enough to cope with that plus extra room for called
functions or fail the build.

Those numbers were picked arbitrarily based on the above 9568 byte
stack frame:

10240 (2.5 * PAGE_SIZE): used to override -Wframe-larger-than whose
default value is 1024.
12288 (3 * PAGE_SIZE): minimum .bss size to contain the stack.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Chris Brandt <Chris.Brandt@renesas.com>
2017-09-10 19:34:53 -04:00

119 lines
3.1 KiB
Makefile

#
# arch/arm/boot/Makefile
#
# This file is included by the global makefile so that you can add your own
# architecture-specific flags and dependencies.
#
# This file is subject to the terms and conditions of the GNU General Public
# License. See the file "COPYING" in the main directory of this archive
# for more details.
#
# Copyright (C) 1995-2002 Russell King
#
OBJCOPYFLAGS :=-O binary -R .comment -S
ifneq ($(MACHINE),)
include $(MACHINE)/Makefile.boot
endif
# Note: the following conditions must always be true:
# ZRELADDR == virt_to_phys(PAGE_OFFSET + TEXT_OFFSET)
# PARAMS_PHYS must be within 4MB of ZRELADDR
# INITRD_PHYS must be in RAM
ZRELADDR := $(zreladdr-y)
PARAMS_PHYS := $(params_phys-y)
INITRD_PHYS := $(initrd_phys-y)
export ZRELADDR INITRD_PHYS PARAMS_PHYS
targets := Image zImage xipImage bootpImage uImage
ifeq ($(CONFIG_XIP_KERNEL),y)
cmd_deflate_xip_data = $(CONFIG_SHELL) -c \
'$(srctree)/$(src)/deflate_xip_data.sh $< $@ || { rm -f $@; false; }'
ifeq ($(CONFIG_XIP_DEFLATED_DATA),y)
quiet_cmd_mkxip = XIPZ $@
cmd_mkxip = $(cmd_objcopy) && $(cmd_deflate_xip_data)
else
quiet_cmd_mkxip = $(quiet_cmd_objcopy)
cmd_mkxip = $(cmd_objcopy)
endif
$(obj)/xipImage: vmlinux FORCE
$(call if_changed,mkxip)
@$(kecho) ' Physical Address of xipImage: $(CONFIG_XIP_PHYS_ADDR)'
$(obj)/Image $(obj)/zImage: FORCE
@echo 'Kernel configured for XIP (CONFIG_XIP_KERNEL=y)'
@echo 'Only the xipImage target is available in this case'
@false
else
$(obj)/xipImage: FORCE
@echo 'Kernel not configured for XIP (CONFIG_XIP_KERNEL!=y)'
@false
$(obj)/Image: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/compressed/vmlinux: $(obj)/Image FORCE
$(Q)$(MAKE) $(build)=$(obj)/compressed $@
$(obj)/zImage: $(obj)/compressed/vmlinux FORCE
$(call if_changed,objcopy)
endif
ifneq ($(LOADADDR),)
UIMAGE_LOADADDR=$(LOADADDR)
else
ifeq ($(CONFIG_ZBOOT_ROM),y)
UIMAGE_LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT)
else
UIMAGE_LOADADDR=$(ZRELADDR)
endif
endif
check_for_multiple_loadaddr = \
if [ $(words $(UIMAGE_LOADADDR)) -ne 1 ]; then \
echo 'multiple (or no) load addresses: $(UIMAGE_LOADADDR)'; \
echo 'This is incompatible with uImages'; \
echo 'Specify LOADADDR on the commandline to build an uImage'; \
false; \
fi
$(obj)/uImage: $(obj)/zImage FORCE
@$(check_for_multiple_loadaddr)
$(call if_changed,uimage)
$(obj)/bootp/bootp: $(obj)/zImage initrd FORCE
$(Q)$(MAKE) $(build)=$(obj)/bootp $@
$(obj)/bootpImage: $(obj)/bootp/bootp FORCE
$(call if_changed,objcopy)
PHONY += initrd install zinstall uinstall
initrd:
@test "$(INITRD_PHYS)" != "" || \
(echo This machine does not support INITRD; exit -1)
@test "$(INITRD)" != "" || \
(echo You must specify INITRD; exit -1)
install:
$(CONFIG_SHELL) $(srctree)/$(src)/install.sh "$(KERNELRELEASE)" \
$(obj)/Image System.map "$(INSTALL_PATH)"
zinstall:
$(CONFIG_SHELL) $(srctree)/$(src)/install.sh "$(KERNELRELEASE)" \
$(obj)/zImage System.map "$(INSTALL_PATH)"
uinstall:
$(CONFIG_SHELL) $(srctree)/$(src)/install.sh "$(KERNELRELEASE)" \
$(obj)/uImage System.map "$(INSTALL_PATH)"
subdir- := bootp compressed dts