openwrt生成固件firmware过程

由于想看看生成各个文件系统格式文件的过程，所以在Target Images中把ext4/jffs2/squashfs都打上了，实际上最后固件使用的文件系统是squashfs+jffs2
Target Images —>

[*] ext4 —>
[*] jffs2 | |
[*] squashfs —>
[*] GZip images
* Image Options *
(48) Root filesystem partition size (in MB)
[ ] Include kernel in root filesystem —-
[ ] Include DTB in root filesystem

用make V=s编译，看最后一段log，就是生成固件和文件系统的过程，下面是log并作了注释

cp $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux.elf $cc/bin/ramips/openwrt-ramips-mt7620-vmlinux.elfcp $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux $cc/bin/ramips/openwrt-ramips-mt7620-vmlinux.bin#内核文件用lzma压缩，生成vmlinux.bin.lzma$cc/staging_dir/host/bin/lzma e $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux -lc1 -lp2 -pb2 $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux.bin.lzma#用mkimage命令根据vmlinux.bin.lzma生成uImage.lzmaLZMA 4.65 : Igor Pavlov : Public domain : 2009-02-03mkimage -A mips -O linux -T kernel -C lzma -a 0x80000000 -e 0x80000000 -n "MIPS OpenWrt Linux-3.18.29" -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux.bin.lzma $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/uImage.lzmaImage Name:   MIPS OpenWrt Linux-3.18.29Created:      Tue May 10 20:43:10 2016Image Type:   MIPS Linux Kernel Image (lzma compressed)Data Size:    1137576 Bytes = 1110.91 kB = 1.08 MBLoad Address: 80000000Entry Point:  80000000#将生成的uImage.lzma复制成openwrt-ramips-mt7620-uImage.bincp $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/uImage.lzma $cc/bin/ramips/openwrt-ramips-mt7620-uImage.bin#用mksquashfs4压缩文件系统squashfs$cc/staging_dir/host/bin/mksquashfs4 $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.squashfs -nopad -noappend -root-owned -comp xz -Xpreset 9 -Xe -Xlc 0 -Xlp 2 -Xpb 2  -b 256k -p '/dev d 755 0 0' -p '/dev/console c 600 0 0 5 1' -processors 1Parallel mksquashfs: Using 1 processorCreating 4.0 filesystem on $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.squashfs, block size 262144.Pseudo file "/dev" exists in source filesystem "$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips/dev".Ignoring, exclude it (-e/-ef) to override.[=============================================================================================================================================================-] 959/959 100%Exportable Squashfs 4.0 filesystem, xz compressed, data block size 262144        compressed data, compressed metadata, compressed fragments, no xattrs        duplicates are removedFilesystem size 4604.89 Kbytes (4.50 Mbytes)        29.59% of uncompressed filesystem size (15562.88 Kbytes)Inode table size 9708 bytes (9.48 Kbytes)        23.48% of uncompressed inode table size (41347 bytes)Directory table size 12216 bytes (11.93 Kbytes)        47.85% of uncompressed directory table size (25528 bytes)Number of duplicate files found 17Number of inodes 1247Number of files 933Number of fragments 30Number of symbolic links  207Number of device nodes 1Number of fifo nodes 0Number of socket nodes 0Number of directories 106Number of ids (unique uids + gids) 1Number of uids 1        root (0)Number of gids 1        root (0)############squashfs文件系统生成成功#################开始生成jffs2-64k文件系统$cc/staging_dir/host/bin/mkfs.jffs2 --little-endian --squash-uids -v -X rtime -X lzma --compression-mode=size -x zlib -D $cc/include/device_table.txt --pad -e 64KiB -o $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-64k -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips -v 2>&1 1>/dev/null | awk '/^.+$/'Compression mode: sizeCompressors:      none             compr: 177 blocks (109257)  decompr: 0 blocks      zlib (prio:80) - compr: 0 blocks (0/0)  decompr: 0 blocks       lzma (prio:70) + compr: 4463 blocks (6551797/15742007)  decompr: 0 blocks      rtime (prio:50) + compr: 10 blocks (5292/7660)  decompr: 0 blocks Compression errors: 0echo -ne '\xde\xad\xc0\xde' >> $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-64k##生成jffs2-128k文件系统$cc/staging_dir/host/bin/mkfs.jffs2 --little-endian --squash-uids -v -X rtime -X lzma --compression-mode=size -x zlib -D $cc/include/device_table.txt --pad -e 128KiB -o $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-128k -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips -v 2>&1 1>/dev/null | awk '/^.+$/'Compression mode: sizeCompressors:      none             compr: 126 blocks (63985)  decompr: 0 blocks      zlib (prio:80) - compr: 0 blocks (0/0)  decompr: 0 blocks       lzma (prio:70) + compr: 4463 blocks (6569958/15781501)  decompr: 0 blocks      rtime (prio:50) + compr: 13 blocks (10252/13438)  decompr: 0 blocks Compression errors: 0echo -ne '\xde\xad\xc0\xde' >> $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-128k#生成ext4文件系统$cc/staging_dir/host/bin/make_ext4fs -l 50331648 -b 4096 -i 6000 -m 0 -J $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.ext4 $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips/Creating filesystem with parameters:    Size: 50331648    Block size: 4096    Blocks per group: 32768    Inodes per group: 6000    Inode size: 256    Journal blocks: 0    Label:     Blocks: 12288    Block groups: 1    Reserved blocks: 0    Reserved block group size: 7Created filesystem with 1256/6000 inodes and 5051/12288 blocks#生成两个jffs2文件系统的raw，但是没看到他怎么使用它$cc/staging_dir/host/bin/mkfs.jffs2 --little-endian --squash-uids -v -X rtime -X lzma --compression-mode=size -x zlib -D $cc/include/device_table.txt -e 64KiB -o $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-64k-raw -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips -v 2>&1 1>/dev/null | awk '/^.+$/'Compression mode: sizeCompressors:      none             compr: 177 blocks (109257)  decompr: 0 blocks      zlib (prio:80) - compr: 0 blocks (0/0)  decompr: 0 blocks       lzma (prio:70) + compr: 4463 blocks (6551797/15742007)  decompr: 0 blocks      rtime (prio:50) + compr: 10 blocks (5292/7660)  decompr: 0 blocks Compression errors: 0$cc/staging_dir/host/bin/mkfs.jffs2 --little-endian --squash-uids -v -X rtime -X lzma --compression-mode=size -x zlib -D $cc/include/device_table.txt -e 128KiB -o $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-128k-raw -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips -v 2>&1 1>/dev/null | awk '/^.+$/'Compression mode: sizeCompressors:      none             compr: 126 blocks (63985)  decompr: 0 blocks      zlib (prio:80) - compr: 0 blocks (0/0)  decompr: 0 blocks       lzma (prio:70) + compr: 4463 blocks (6569958/15781501)  decompr: 0 blocks      rtime (prio:50) + compr: 13 blocks (10252/13438)  decompr: 0 blocks Compression errors: 0#用dd生成最终的squashfs文件系统dd if=$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.squashfs of=$cc/bin/ramips/openwrt-ramips-mt7620-root.squashfs bs=128k conv=sync35+1 records in36+0 records out4718592 bytes (4.7 MB) copied, 0.0153264 s, 308 MB/scp $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/linux-3.18.29/scripts/dtc/dtc -O dtb -o $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/MT7620a.dtb ../dts/MT7620a.dts#patch-dtb命令$cc/staging_dir/host/bin/patch-dtb $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/MT7620a.dtb#lzma生成vmlinux-mt7620a.bin.lzma$cc/staging_dir/host/bin/lzma e $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a -lc1 -lp2 -pb2 $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a.bin.lzmaLZMA 4.65 : Igor Pavlov : Public domain : 2009-02-03#mkimage根据vmlinux-mt7620a.bin.lzma生成vmlinux-mt7620a.uImagemkimage -A mips -O linux -T kernel -C lzma -a 0x80000000 -e 0x80000000 -n "MIPS OpenWrt Linux-3.18.29" -d $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a.bin.lzma $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a.uImageImage Name:   MIPS OpenWrt Linux-3.18.29Created:      Tue May 10 20:43:41 2016Image Type:   MIPS Linux Kernel Image (lzma compressed)Data Size:    1139383 Bytes = 1112.68 kB = 1.09 MBLoad Address: 80000000Entry Point:  80000000#组合vmlinux-mt7620a.uImage和root.squashfs生成最终固件openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bincat $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/vmlinux-mt7620a.uImage $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.squashfs > $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin#padjffs2命令处理固件$cc/staging_dir/host/bin/padjffs2 $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin 4 8 16 64 128 256padding image to 00596000padding image to 00598000padding image to 005a0000padding image to 005c0000if [ `stat -c%s "$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin"` -gt 8060928 ]; then echo "Warning: $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin is too big" >&2; else cp -fpR $cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin $cc/bin/ramips/openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin; fi#dd处理root.jffs2-64k生成最终的文件系统dd if=$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-64k of=$cc/bin/ramips/openwrt-ramips-mt7620-root.jffs2-64k bs=128k conv=sync54+1 records in55+0 records out7208960 bytes (7.2 MB) copied, 0.00730228 s, 987 MB/s#dd处理root.jffs2-128k，生成最终的文件系统dd if=$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.jffs2-128k of=$cc/bin/ramips/openwrt-ramips-mt7620-root.jffs2-128k bs=128k conv=sync54+1 records in55+0 records out7208960 bytes (7.2 MB) copied, 0.00964141 s, 748 MB/s#dd处理root.ext4，生成最终的文件系统dd if=$cc/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/root.ext4 of=$cc/bin/ramips/openwrt-ramips-mt7620-root.ext4 bs=128k conv=sync384+0 records in384+0 records out50331648 bytes (50 MB) copied, 0.171708 s, 293 MB/s( cd $cc/bin/ramips ; find -maxdepth 1 -type f \! -name 'md5sums'  -printf "%P\n" | sort | xargs md5sum --binary > md5sums )( cd $cc/bin/ramips ; find -maxdepth 1 -type f \! -name 'md5sums'  -printf "%P\n" | sort | xargs openssl dgst -sha256 > sha256sums )make[5]: Leaving directory `$cc/target/linux/ramips/image'make[4]: Leaving directory `$cc/target/linux/ramips'make[3]: Leaving directory `$cc/target/linux'make[2]: Leaving directory `$cc'export MAKEFLAGS= ;make -w -r package/indexmake[2]: Entering directory `$cc'Generating package index...Generating index for package ./IPKG_BUILD.20733/pkg_file.ipkGenerating index for package ./base-files_157.2-unknown_ramips_24kec.ipkGenerating index for package ./busybox_1.23.2-1_ramips_24kec.ipk

从Makefile剖析生成firmware

firmware由kernel和rootfs两个部分组成，要对两个部分先分别处理，然后再合并成一个.bin文件。先看一下这个流程。

“target/linux/ramips/image/Makefile” 文件中的最后一句：(eval(call BuildImage))，将BuildImage展开在这里。BuildImage定义在 include/image.mk 文件中，其中定义了数个目标的规则。

define BuildImage    compile: compile-targets FORCE        **$(call Build/Compile)**    install: compile install-targets FORCE ...     $(call Image/BuildKernel)   ## 处理vmlinux ...     $(call Image/mkfs/squashfs) ## 生成squashfs，并与vmlinux合并成一个.bin文件 ...     endef

处理vmlinux: Image/BuildKernel

target/linux/ramips/image/Makefile:

define Image/BuildKernel    cp $(KDIR)/vmlinux.elf $(BIN_DIR)/$(VMLINUX).elf    cp $(KDIR)/vmlinux $(BIN_DIR)/$(VMLINUX).bin     $(call CompressLzma,$(KDIR)/vmlinux,$(KDIR)/vmlinux.bin.lzma)     $(call MkImage,lzma,$(KDIR)/vmlinux.bin.lzma,$(KDIR)/uImage.lzma)    cp $(KDIR)/uImage.lzma $(BIN_DIR)/$(UIMAGE).binifneq ($(CONFIG_TARGET_ROOTFS_INITRAMFS),)    cp $(KDIR)/vmlinux-initramfs.elf $(BIN_DIR)/$(VMLINUX)-initramfs.elf    cp $(KDIR)/vmlinux-initramfs $(BIN_DIR)/$(VMLINUX)-initramfs.bin      $(call CompressLzma,$(KDIR)/vmlinux-initramfs,$(KDIR)/vmlinux-initramfs.bin.lzma)      $(call MkImage,lzma,$(KDIR)/vmlinux-initramfs.bin.lzma,$(KDIR)/uImage-initramfs.lzma)    cp $(KDIR)/uImage-initramfs.lzma $(BIN_DIR)/$(UIMAGE)-initramfs.binendif $(call Image/Build/Initramfs) endef

lzma压缩内核

build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/ 目录中:

lzma e vmlinux -lc1 -lp2 -pb2 vmlinux.bin.lzma

MkImage

build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/ 目录中：

mkimage -A mips -O linux -T  kernel -C lzma -a 0x80000000 -e 0x80000000 -n "MIPS OpenWrt Linux-3.14.18" -d vmlinux.bin.lzma uImage.lzma

copy

VMLINUX:=$(IMG_PREFIX)-vmlinux --> openwrt-ramips-mt7620a-vmlinux UIMAGE:=$(IMG_PREFIX)-uImage --> openwrt-ramips-mt7620a-uImagecp $(KDIR)/uImage.lzma $(BIN_DIR)/$(UIMAGE).bin

把uImage.lzma复制到bin/ramips/目录下：
cp $(KDIR)/uImage.lzma bin/ramips/openwrt-ramips-mt7620a-uImage

制作squashfs，生成.bin: $(call Image/mkfs/squashfs)

define Image/mkfs/squashfs    @mkdir -p $(TARGET_DIR)/overlay   $(STAGING_DIR_HOST)/bin/mksquashfs4 $(TARGET_DIR) $(KDIR)/root.squashfs -nopad -noappend -root-owned -comp $(SQUASHFSCOMP) $(SQUASHFSOPT) -processors    $(if $(CONFIG_PKG_BUILD_JOBS),$(CONFIG_PKG_BUILD_JOBS),1)       $(call Image/Build,squashfs)   endifmkdir -p $(TARGET_DIR)/overlaymkdir -p build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips/overlay

mkdir -p $(TARGET_DIR)/overlay

 mkdir -p build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/root-ramips/overlay

mksquashfs4

$(STAGING_DIR_HOST)/bin/mksquashfs4 $(TARGET_DIR) $(KDIR)/root.squashfs -nopad -noappend -root-owned -comp $(SQUASHFSCOMP) $(SQUASHFSOPT) -processors $(if $(CONFIG_PKG_BUILD_JOBS),$(CONFIG_PKG_BUILD_JOBS),1)

制作squashfs文件系统，生成root.squashfs:

mksquashfs4 root-ramips root.squashfs -nopad -noappend -root-owned -comp gzip -b 256k -p '/dev d 755 0 0' -p '/dev/console c 600 0 0 5 1' -processors 1$(call Image/Build,squashfs)

$(call Image/Build,squashfs)

在 target/linux/ramips/image/Makefile 中：

define Image/Build $(call Image/Build/$(1))    dd if=$(KDIR)/root.$(1) of=$(BIN_DIR)/$(IMG_PREFIX)-root.$(1) bs=128k conv=sync $(call Image/Build/Profile/$(PROFILE),$(1))endefdd if=(KDIR)/root.squashfsof=(BIN_DIR)/$(IMG_PREFIX)-root.squashfs bs=128k conv=syncdd if=build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/root.squashfs of=bin/ramips/openwrt-ramips-mt7620-root.squashfs bs=128k conv=sync(callImage/Build/Profile/(PROFILE),squashfs)

dd if=(KDIR)/root.squashfsof=(BIN_DIR)/$(IMG_PREFIX)-root.squashfs bs=128k conv=sync
dd if=build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/root.squashfs of=bin/ramips/openwrt-ramips-mt7620-root.squashfs bs=128k conv=sync

(callImage/Build/Profile/(PROFILE),squashfs)
target/linux/ramips/mt7620a/profiles/00-default.mk, 中调用 Profile 函数：(eval(call Profile,Default))

include/target.mk 中定义了 Profile 函数， 其中令 PROFILE=Default

define Image/Build/Profile/Default    $(call Image/Build/Profile/MT7620a,$(1)) ... endef

规则依赖序列如下

$(call Image/Build/Profile/$(PROFILE),squashfs)  --> $(call BuildFirmware/Default8M/squashfs,squashfs,mt7620a,MT7620a)  --> $(call BuildFirmware/OF,squashfs,mt7620a,MT7620a,8060928)  --> $(call MkImageLzmaDtb,mt7620a,MT7620a)  --> $(call PatchKernelLzmaDtb,mt7620a,MT7620a)  --> $(call MkImage,lzma,$(KDIR)/vmlinux-mt7620a.bin.lzma,$(KDIR)/vmlinux-mt7620a.uImage)  --> $(call MkImageSysupgrade/squashfs,squashfs,mt7620a,8060928)

其中的主要步骤：

• 复制： cp (KDIR)/vmlinux(KDIR)/vmlinux-mt7620a
• 生成dtb文件： (LINUXDIR)/scripts/dtc/dtc?Odtb?o(KDIR)/MT7620a.dtb ../dts/MT7620a.dts
• 将内核与dtb文件合并：(STAGINGDIRHOST)/bin/patch?dtb(KDIR)/vmlinux-mt7620a $(KDIR)/MT7620a.dtb
• 使用lzma压缩：(callCompressLzma,(KDIR)/vmlinux-mt7620a,$(KDIR)/vmlinux-mt7620a.bin.lzma
• 将lzma压缩后的文件经过mkimage工具处理，即在头部添加uboot可识别的信息。

接下来就是合并生成firmware固件了：

MkImageSysupgrade/squashfs, squashfs, mt7620a,8060928

cat vmlinux-mt7620a.uImage root.squashfs > openwrt-ramips-mt7620-mt7620a-squashfs-sysupgrade.bin
–> 制作squashfs bin文档, 并确认它的大小 < 8060928 才是有效的，否则报错。

总结： 整个流程下来，其实最烦索的还是对内核生成文件vmlinux的操作，经过了objcopy, patch-dtb, lzma, mkimage 等过程生成一个uImage，再与mksquashfs工具制作的文件系统rootfs.squashfs合并。

转：http://www.openwrtdl.com/wordpress/openwrt%E7%94%9F%E6%88%90%E5%9B%BA%E4%BB%B6firmware%E6%B5%81%E7%A8%8B