Ubuntu环境下为arm64架构树莓派4交叉编译Qt5的技术问询

主机环境 #

系统版本：Ubuntu 20.04 x64

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   43 bits physical, 48 bits virtual
CPU(s):                          4
On-line CPU(s) list:             0-3
Thread(s) per core:              2
Core(s) per socket:              2
Socket(s):                       1
NUMA node(s):                    1
Vendor ID:                       AuthenticAMD
CPU family:                      23
Model:                           32
Model name:                      AMD Athlon Silver 3050e with Radeon Graphics
Stepping:                        1
Frequency boost:                 enabled
CPU MHz:                         946.324
CPU max MHz:                     1400,0000
CPU min MHz:                     1000,0000
BogoMIPS:                        2794.78
Virtualization:                  AMD-V
L1d cache:                       64 KiB
L1i cache:                       128 KiB
L2 cache:                        1 MiB
L3 cache:                        4 MiB
NUMA node0 CPU(s):               0-3
Vulnerability Itlb multihit:     Not affected
Vulnerability L1tf:              Not affected
Vulnerability Mds:               Not affected
Vulnerability Meltdown:          Not affected
Vulnerability Mmio stale data:   Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Retpolines, IBPB conditional, STIBP always-on, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate sme ssbd sev ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca

目标设备 #

设备配置：搭载Ubuntu 22.04 aarch64系统的树莓派4

Architecture:            aarch64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                  4
On-line CPU(s) list:   0-3
Vendor ID:               ARM
Model name:            Cortex-A72
  Model:               3
  Thread(s) per core:  1
  Core(s) per cluster: 4
  Socket(s):           -
  Cluster(s):          1
  Stepping:            r0p3
  CPU max MHz:         1800,0000
  CPU min MHz:         600,0000
  BogoMIPS:            108.00
  Flags:               fp asimd evtstrm crc32 cpuid
Caches (sum of all):     
  L1d:                   128 KiB (4 instances)
  L1i:                   192 KiB (4 instances)
  L2:                    1 MiB (1 instance)
Vulnerabilities:         
  Itlb multihit:         Not affected
  L1tf:                  Not affected
  Mds:                   Not affected
  Meltdown:              Not affected
  Spec store bypass:     Vulnerable
  Spectre v1:            Mitigation; __user pointer sanitization
  Spectre v2:            Vulnerable
  Srbds:                 Not affected
  Tsx async abort:       Not affected

• 交叉编译器选择：选用Linaro 7分支的x86_64_aarch64-linux-gnu稳定版（具体版本为gcc-linaro-7.5.0-2019.12）即可，该版本对Cortex-A72架构优化完善，和Ubuntu 22.04自带的glibc 2.35版本兼容性最好，不会出现编译后程序无法在目标机运行的ABI不匹配问题。
• rsync同步目录：双端均为Ubuntu系统时，不需要同步Raspbian场景下的专用固件目录，仅需同步目标机以下目录到主机的交叉编译sysroot路径即可，同步时必须加-a参数保留软链接，避免链接断裂导致编译报错：
  • /lib：系统基础运行库
  • /usr/lib：用户态安装的所有依赖库
  • /usr/include：系统及第三方依赖的头文件
  • 若目标机/opt路径下安装了自定义依赖（如GPU驱动、专用SDK），也需要一并同步
• Qt5 ./configure 适配参数：配置时需要传入的核心参数如下，注意将占位路径替换为本地实际路径：

  -opensource -confirm-license -release \
  -device linux-rasp-pi3-aarch64-gnu++ \
  -device-option CROSS_COMPILE=<交叉编译器bin目录下的aarch64-linux-gnu-前缀路径> \
  -sysroot <本地rsync同步的目标系统根目录路径> \
  -prefix /usr/local/qt5 \
  -extprefix <主机端存放编译后可部署到目标机的Qt文件路径> \
  -hostprefix <主机端存放Qt宿主工具（qmake、moc、rcc等）的路径> \
  -no-use-gold-linker -opengl es2 -eglfs -kms \
  -no-pch -qpa eglfs
  

  其中-opengl es2 -kms -eglfs参数是为了适配树莓派4的VC4 GPU硬件加速，避免编译后Qt程序无法调用图形硬件。
• mkspec设备配置选择：选择linux-rasp-pi3-aarch64-gnu++配置作为基础适配即可。该配置原本针对64位树莓派3的Cortex-A53架构编写，树莓派4所用的Cortex-A72是ARMv8-A架构的向前兼容超集，仅需要将配置文件中的-mtune=cortex-a53修改为-mtune=cortex-a72即可，其余编译选项、EGL/GLES库路径配置和Ubuntu 22.04 aarch64 for 树莓派4的环境完全匹配，无需大规模修改。

内容的提问来源于stack exchange，提问作者ZeusBios