0.頂層Makefile增加交叉編譯器
頂層makefile：
ARCH ?= $(SUBARCH)
CROSS_COMPILE ?= $(CONFIG_CROSS_COMPILE:"%"=%)
改為：
ARCH ?= arm64
CROSS_COMPILE ?= aarch64-linux-gnu-
1.生成.config
***_defconfig文件一般的芯片都有，找到以后，用如下命令，其實就是拷貝到頂層目錄，並命名為.config,里面包含一堆配置，make時讀取。
***_defconfig文件在 arch/arm64/configs/目錄下
[liuwanpeng@localhost linux]$ make xilinx_zynqmp_defconfig O=./output/
#
# configuration written to .config
#
單獨輸出到其他文件件有助於源碼進行git管理，否則亂的文件。
2.make
[liuwanpeng@localhost linux]$ make LOADADDR=0x8000
默認生成Image，若想生成uImage，需要加上uImage后綴
[liuwanpeng@localhost linux]$ make LOADADDR=0x8000 uImage
make: *** 沒有規則可以創建目標“uImage”。 停止。
2.1 uImage無法生成問題
mpsoc不像ZYNQ，把make uImage集成到makefile里了，可以單獨執行mkimage指令。
mkimage是uboot編譯后，生成的工具，拷貝到/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所在目錄執行如下命令即可：
mkimage -n 'xlnx-linux' -A arm64 -O linux -T kernel -C none -a 0x00080000 -e 0x00080000 -d Image uImage
2.2 幾種linux鏡像格式
- vmlinux 未壓縮內核鏡像文件，
- zImage zImage是一般情況下默認的壓縮內核映像文件，壓縮vmlinux，加上一段解壓啟動代碼得到，只能從0X0地址運行
- uImage uImage是u-boot使用bootm命令引導的Linux壓縮內核映像文件格式， 使用工具mkimage（uboot提供此工具）對普通的壓縮內核映像文件（zImage）加工而得。可以由bootm命令從任意地址解壓啟動內核。由於bootloader一般要占用0x0地址，所以，uImage相比zImage的好處就是可以和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，整個目錄都編譯了
make xxx.dtb
不好用了，具體原因還未定位，估計是makefile體系的問題
可以用dtc命令編譯或反編譯特定的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：
反匯編，由dtb生成dts，反之亦然
dtc -I dtb -O dts -o zynqmp-zcu102.dts zynqmp-zcu102.dtb