Commit 4d2acfbf authored by David Woodhouse's avatar David Woodhouse Committed by David Woodhouse

firmware: Add CONFIG_EXTRA_FIRMWARE option

This allows arbitrary firmware files to be included in the static kernel
where the firmware loader can find them without requiring userspace to
be alive.

(Updated and CONFIG_EXTRA_FIRMWARE_DIR added with lots of help from
Johannes Berg).
Signed-off-by: default avatarDavid Woodhouse <>
Signed-off-by: default avatarJohannes Berg <>
parent 5658c769
......@@ -450,7 +450,7 @@ scripts: scripts_basic include/config/auto.conf
# Objects we will link into vmlinux / subdirs we need to visit
init-y := init/
drivers-y := drivers/ sound/
drivers-y := drivers/ sound/ firmware/
net-y := net/
libs-y := lib/
core-y := usr/
......@@ -34,6 +34,45 @@ config FW_LOADER
require userspace firmware loading support, but a module built outside
the kernel tree does.
string "External firmware blobs to build into the kernel binary"
depends on FW_LOADER
This option allows firmware to be built into the kernel, for the
cases where the user either cannot or doesn't want to provide it from
userspace at runtime (for example, when the firmware in question is
required for accessing the boot device, and the user doesn't want to
use an initrd).
This option is a string, and takes the (space-separated) names of the
firmware files -- the same names which appear in MODULE_FIRMWARE()
and request_firmware() in the source. These files should exist under
the directory specified by the EXTRA_FIRMWARE_DIR option, which is
by default the firmware/ subdirectory of the kernel source tree.
So, for example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin",
copy the usb8388.bin file into the firmware/ directory, and build the
kernel. Then any request_firmware("usb8388.bin") will be
satisfied internally without needing to call out to userspace.
WARNING: If you include additional firmware files into your binary
kernel image which are not available under the terms of the GPL,
then it may be a violation of the GPL to distribute the resulting
image -- since it combines both GPL and non-GPL work. You should
consult a lawyer of your own before distributing such an image.
string "Firmware blobs root directory"
depends on EXTRA_FIRMWARE != ""
default "firmware"
This option controls the directory in which the kernel build system
looks for the firmware files listed in the EXTRA_FIRMWARE option.
The default is the firmware/ directory in the kernel source tree,
but by changing this option you can point it elsewhere, such as
the /lib/firmware/ directory or another separate directory
containing firmware files.
bool "Driver Core verbose debug messages"
depends on DEBUG_KERNEL
# kbuild file for firmware/
# Create $(fwabs) from $(CONFIG_EXTRA_FIRMWARE_DIR) -- if it doesn't have a
# leading /, it's relative to $(srctree).
fwdir := $(subst ",,$(CONFIG_EXTRA_FIRMWARE_DIR))
fwabs := $(addprefix $(srctree)/,$(filter-out /%,$(fwdir)))$(filter /%,$(fwdir))
fw-external-y := $(subst ",,$(CONFIG_EXTRA_FIRMWARE))
firmware-y := $(fw-external-y) $(fw-shipped-y)
firmware-dirs := $(sort $(patsubst %,$(objtree)/$(obj)/%/,$(dir $(firmware-y) $(fw-shipped-))))
quiet_cmd_mkdir = MKDIR $(patsubst $(objtree)/%,%,$@)
cmd_mkdir = mkdir -p $@
quiet_cmd_ihex = IHEX $@
cmd_ihex = $(OBJCOPY) -Iihex -Obinary $< $@
quiet_cmd_fwbin = MK_FW $@
cmd_fwbin = FWNAME="$(patsubst firmware/%.gen.S,%,$@)"; \
FWSTR="$(subst /,_,$(subst .,_,$(subst -,_,$(patsubst \
firmware/%.gen.S,%,$@))))"; \
ASM_WORD=$(if $(CONFIG_64BIT),.quad,.long); \
ASM_ALIGN=$(if $(CONFIG_64BIT),3,2); \
PROGBITS=$(if $(CONFIG_ARM),%,@)progbits; \
echo "/* Generated by firmware/Makefile */" > $@;\
echo " .section .rodata" >>$@;\
echo " .p2align $${ASM_ALIGN}" >>$@;\
echo "_fw_$${FWSTR}_bin:" >>$@;\
echo " .incbin \"$(2)\"" >>$@;\
echo "_fw_end:" >>$@;\
echo " .section .rodata.str,\"aMS\",$${PROGBITS},1" >>$@;\
echo " .p2align $${ASM_ALIGN}" >>$@;\
echo "_fw_$${FWSTR}_name:" >>$@;\
echo " .string \"$$FWNAME\"" >>$@;\
echo " .section .builtin_fw,\"a\",$${PROGBITS}" >>$@;\
echo " .p2align $${ASM_ALIGN}" >>$@;\
echo " $${ASM_WORD} _fw_$${FWSTR}_name" >>$@;\
echo " $${ASM_WORD} _fw_$${FWSTR}_bin" >>$@;\
echo " $${ASM_WORD} _fw_end - _fw_$${FWSTR}_bin" >>$@;
# One of these files will change, or come into existence, whenever
# the configuration changes between 32-bit and 64-bit. The .S files
# need to change when that happens.
wordsize_deps := $(wildcard include/config/64bit.h include/config/32bit.h \
include/config/ppc32.h include/config/ppc64.h \
include/config/superh32.h include/config/superh64.h \
include/config/x86_32.h include/config/x86_64.h)
# Workaround for make < 3.81, where .SECONDEXPANSION doesn't work.
# It'll end up depending on these targets, so make them a PHONY rule which
# depends on _all_ the directories in $(firmware-dirs), and it'll work out OK.
PHONY += $(objtree)/$$(%) $(objtree)/$(obj)/$$(%)
$(objtree)/$$(%) $(objtree)/$(obj)/$$(%): $(firmware-dirs)
# For the $$(dir %) trick, where we need % to be expanded first.
$(patsubst %,$(obj)/%.gen.S, $(fw-shipped-y)): %: $(wordsize_deps) \
| $(objtree)/$$(dir %)
$(call cmd,fwbin,$(patsubst %.gen.S,%,$@))
$(patsubst %,$(obj)/%.gen.S, $(fw-external-y)): %: $(wordsize_deps) \
include/config/builtin/firmware/dir.h | $(objtree)/$$(dir %)
$(call cmd,fwbin,$(fwabs)/$(patsubst $(obj)/%.gen.S,%,$@))
# The .o files depend on the binaries directly; the .S files don't.
$(patsubst %,$(obj)/%.gen.o, $(fw-shipped-y)): %.gen.o: %
$(patsubst %,$(obj)/%.gen.o, $(fw-external-y)): $(obj)/%.gen.o: $(fwdir)/%
$(obj)/%: $(obj)/%.ihex | $(objtree)/$(obj)/$$(dir %)
$(call cmd,ihex)
$(call cmd,mkdir)
obj-y := $(patsubst %,%.gen.o, $(firmware-y))
# Remove .S files and binaries created from ihex
# (during 'make clean' .config isn't included so they're all in $(fw-shipped-))
targets := $(fw-shipped-) $(patsubst $(obj)/%,%, \
$(shell find $(obj) -name \*.gen.S 2>/dev/null))
# Without this, built-in.o won't be created when it's empty, and the
# final vmlinux link will fail.
obj-n := dummy
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