MPSOC之6——开发流程linux编译

0.顶层Makefile增加交叉编译器

顶层makefile：

ARCH		?= $(SUBARCH)
CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)

改为：

ARCH		?= arm64
CROSS_COMPILE	?= aarch64-linux-gnu-

1.生成.config

***_defconfig文件一般的芯片都有，找到以后，用如下命令，其实就是拷贝到顶层目录，并命名为.config,里面包含一堆配置，make时读取。

***_defconfig文件在 arch/arm64/configs/目录下

[liuwanpeng@localhost linux]$ make xilinx_zynqmp_defconfig O=./output/
#
# configuration written to .config
#

单独输出到其他文件件有助于源码进行git管理，否则乱的文件。

2.make

[liuwanpeng@localhost linux]$ make LOADADDR=0x8000

默认生成Image，若想生成uImage，需要加上uImage后缀

[liuwanpeng@localhost linux]$ make LOADADDR=0x8000 uImage
make: *** 没有规则可以创建目标“uImage”。 停止。

2.1 uImage无法生成问题

mpsoc不像ZYNQ，把make uImage集成到makefile里了，可以单独执行mkimage指令。

mkimage是uboot编译后，生成的工具，拷贝到/usr/bin里

[liuwanpeng@localhost tools]$ mkimage
Error: Missing output filename
Usage: mkimage -l image
          -l ==> list image header information
       mkimage [-x] -A arch -O os -T type -C comp -a addr -e ep -n name -d data_file[:data_file...] image
          -A ==> set architecture to 'arch'
          -O ==> set operating system to 'os'
          -T ==> set image type to 'type'
          -C ==> set compression type 'comp'
          -a ==> set load address to 'addr' (hex)
          -e ==> set entry point to 'ep' (hex)
          -n ==> set image name to 'name'
          -d ==> use image data from 'datafile'
          -x ==> set XIP (execute in place)
       mkimage [-D dtc_options] [-f fit-image.its|-f auto|-F] [-b <dtb> [-b <dtb>]] [-i <ramdisk.cpio.gz>] fit-image
           <dtb> file is used with -f auto, it may occur multiple times.
          -D => set all options for device tree compiler
          -f => input filename for FIT source
          -i => input filename for ramdisk file
Signing / verified boot not supported (CONFIG_FIT_SIGNATURE undefined)
       mkimage -V ==> print version information and exit
Use -T to see a list of available image types

在Image所在目录执行如下命令即可：

 mkimage -n 'xlnx-linux' -A arm64 -O linux -T kernel -C none -a 0x00080000 -e 0x00080000 -d Image uImage

2.2 几种linux镜像格式

• vmlinux 未压缩内核镜像文件，
• zImage zImage是一般情况下默认的压缩内核映像文件，压缩vmlinux，加上一段解压启动代码得到，只能从0X0地址运行
• uImage uImage是u-boot使用bootm命令引导的Linux压缩内核映像文件格式， 使用工具mkimage（uboot提供此工具）对普通的压缩内核映像文件（zImage）加工而得。可以由bootm命令从任意地址解压启动内核。由于bootloader一般要占用0x0地址，所以，uImage相比zImage的好处就是可以和bootloader共存。

3. dts文件

dts文件在arch/arm64/boot/dts中

make dtbs

可以生成dtb文件，整个目录都编译了

make xxx.dtb

不好用了，具体原因还未定位，估计是makefile体系的问题

可以用dtc命令编译或反编译特定的dtb文件

liuwanpeng@liuwanpeng-virtual-machine:~/work/linux/output/arch/arm64/boot/dts/xilinx$ dtc --help
Usage: dtc [options] <input file>

Options: -[qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv]
  -q, --quiet
	Quiet: -q suppress warnings, -qq errors, -qqq all
  -I, --in-format <arg>
	Input formats are:
		dts - device tree source text
		dtb - device tree blob
		fs  - /proc/device-tree style directory
  -o, --out <arg>
	Output file
  -O, --out-format <arg>
	Output formats are:
		dts - device tree source text
		dtb - device tree blob
		asm - assembler source
  -V, --out-version <arg>
	Blob version to produce, defaults to 17 (for dtb and asm output)
  -d, --out-dependency <arg>
	Output dependency file
  -R, --reserve <arg>
	Make space for <number> reserve map entries (for dtb and asm output)
  -S, --space <arg>
	Make the blob at least <bytes> long (extra space)
  -p, --pad <arg>
	Add padding to the blob of <bytes> long (extra space)
  -b, --boot-cpu <arg>
	Set the physical boot cpu
  -f, --force
	Try to produce output even if the input tree has errors
  -i, --include <arg>
	Add a path to search for include files
  -s, --sort
	Sort nodes and properties before outputting (useful for comparing trees)
  -H, --phandle <arg>
	Valid phandle formats are:
		legacy - "linux,phandle" properties only
		epapr  - "phandle" properties only
		both   - Both "linux,phandle" and "phandle" properties
  -W, --warning <arg>
	Enable/disable warnings (prefix with "no-")
  -E, --error <arg>
	Enable/disable errors (prefix with "no-")
  -h, --help
	Print this help and exit
  -v, --version
	Print version and exit

例如：

反汇编，由dtb生成dts，反之亦然

dtc -I dtb -O dts -o zynqmp-zcu102.dts zynqmp-zcu102.dtb