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Date: Wed, 28 May 2008 14:46:03 +0300
From: David Woodhouse <dwmw2@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: sam@...nborg.org, alan@...rguk.ukuu.org.uk,
akpm@...ux-foundation.org, johannes@...solutions.net
Subject: Re: [PATCHv4 27/28] firmware: Add CONFIG_BUILTIN_FIRMWARE option
More feedback... Andrew wanted the help text to be a little more...
well, helpful. And Johannes wanted to add a CONFIG_BUILTIN_FIRMWARE_DIR
option, which lets you just point it at /lib/firmware or somewhere else
outside the kernel tree. And we fixed up a bunch of other details, like
the dependencies on directories, and the fact that the .S file doesn't
actually need to change when the binary blob does.
I even made the Makefile fit in 80 characters. It's going to make your
brain hurt either way -- but that's normal for kernel Makefiles.
commit 4311743f8ef92ab462c06a9dd2ff8e0d735b3dae
Author: David Woodhouse <dwmw2@...radead.org>
Date: Fri May 23 13:58:12 2008 +0100
firmware: Add CONFIG_BUILTIN_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_BUILTIN_FIRMWARE_DIR added with lots of help from
Johannes Berg).
Signed-off-by: David Woodhouse <dwmw2@...radead.org>
Signed-off-by: Johannes Berg <johannes@...solutions.net>
diff --git a/Makefile b/Makefile
index 20b3235..ac2ab7e 100644
--- a/Makefile
+++ b/Makefile
@@ -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/
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index d7da109..f204ae7 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -34,6 +34,39 @@ config FW_LOADER
require userspace firmware loading support, but a module built outside
the kernel tree does.
+config BUILTIN_FIRMWARE
+ string "Firmware blobs to build into the kernel binary"
+ depends on FW_LOADER
+ help
+ 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 BUILTIN_FIRMWARE_DIR option, which is
+ by default the firmware/ subdirectory of the kernel source tree.
+
+ So, for example, you might set CONFIG_BUILTIN_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.
+
+config BUILTIN_FIRMWARE_DIR
+ string "Firmware blobs root directory"
+ depends on BUILTIN_FIRMWARE != ""
+ default "firmware"
+ help
+ This option controls the directory in which the kernel build system
+ looks for the firmware files listed in the BUILTIN_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.
+
config DEBUG_DRIVER
bool "Driver Core verbose debug messages"
depends on DEBUG_KERNEL
diff --git a/firmware/Makefile b/firmware/Makefile
new file mode 100644
index 0000000..c79bbe7
--- /dev/null
+++ b/firmware/Makefile
@@ -0,0 +1,86 @@
+#
+# kbuild file for firmware/
+#
+
+# Create $(fwdir) from $(CONFIG_BUILTIN_FIRMWARE_DIR) -- if it doesn't have a
+# leading /, it's relative to $(srctree).
+fwdir := $(subst ",,$(CONFIG_BUILTIN_FIRMWARE_DIR))
+fwabs := $(addprefix $(srctree)/,$(filter-out /%,$(fwdir)))$(filter /%,$(fwdir))
+
+fw-external-y := $(subst ",,$(CONFIG_BUILTIN_FIRMWARE))
+
+firmware-y := $(fw-external-y) $(fw-shipped-y)
+firmware-dirs := $(sort $(patsubst %,$(objtree)/$(obj)/%/,$(dir $(firmware-y))))
+
+quiet_cmd_mkdir = MKDIR $(subst $(srctree)/,,$@)
+ cmd_mkdir = mkdir -p $@
+
+quiet_cmd_ihex = IHEX $@
+ cmd_ihex = objcopy -Iihex -Obinary $< $@
+
+ifdef CONFIG_64BIT
+ASM_WORD := .quad
+ASM_ALIGN := 3
+else
+ASM_WORD := .long
+ASM_ALIGN := 2
+endif
+
+quiet_cmd_fwbin = MK_FW $@
+ cmd_fwbin = FWNAME="$(patsubst firmware/%.S,%,$@)"; \
+ FWSTR="$(subst /,_,$(subst .,_,$(patsubst \
+ firmware/%.S,%,$@)))"; \
+ echo "/* Generated by firmware/Makefile */" > $@;\
+ echo " .section .rodata" >>$@;\
+ echo " .align $(ASM_ALIGN)" >>$@;\
+ echo "_fw_$${FWSTR}_bin:" >>$@;\
+ echo " .incbin \"$(2)\"" >>$@;\
+ echo "_fw_end:" >>$@;\
+ echo " .section .rodata.str,\"aMS\",@progbits,1" >>$@;\
+ echo " .align $(ASM_ALIGN)" >>$@;\
+ echo "_fw_$${FWSTR}_name:" >>$@;\
+ echo " .string \"$$FWNAME\"" >>$@;\
+ echo " .section .builtin_fw,\"a\",@progbits" >>$@;\
+ echo " .align $(ASM_ALIGN)" >>$@;\
+ echo " $(ASM_WORD) _fw_$${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)
+
+# For the $$(dir %) trick, where we need % to be expanded first.
+.SECONDEXPANSION:
+
+$(patsubst %,$(obj)/%.S, $(fw-shipped-y)): %: $(wordsize_deps) \
+ | $(objtree)/$$(dir %)
+ $(call cmd,fwbin,$(patsubst %.S,%,$@))
+$(patsubst %,$(obj)/%.S, $(fw-external-y)): %: $(wordsize_deps) \
+ include/config/builtin/firmware/dir.h | $(objtree)/$$(dir %)
+ $(call cmd,fwbin,$(fwabs)/$(patsubst $(obj)/%.S,%,$@))
+
+# The .o files depend on the binaries directly; the .S files don't.
+$(patsubst %,$(obj)/%.o, $(fw-shipped-y)): %.o: %
+$(patsubst %,$(obj)/%.o, $(fw-external-y)): $(obj)/%.o: $(fwdir)/%
+
+$(obj)/%: $(obj)/%.ihex | $(objtree)/$(obj)/$$(dir %)
+ $(call cmd,ihex)
+
+$(firmware-dirs):
+ $(call cmd,mkdir)
+
+obj-y := $(patsubst %,%.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 := $(patsubst $(obj)/%,%, $(shell find $(obj) -name \*.S 2>/dev/null))
+targets += $(fw-shipped-)
+
+# Without this, built-in.o won't be created when it's empty, and the
+# final vmlinux link will fail.
+obj-n := dummy
--
dwmw2
--
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