ARM学习笔记-静态库的生成与调用

仅用于记录开发过程中遇到的一些问题，方便日后参考。

      编译好A15的静态库然后在工程中调用，出现问题：

makefile:149: recipe for target 'rtos_template_app_am572x_a15.out' failed
c:/ti/gcc-arm-none-eabi-6-2017-q1-update/bin/../lib/gcc/arm-none-eabi/6.3.1/../../../../arm-none-eabi/bin/ld.exe: error: rtos_template_app_am572x_a15.out uses VFP register arguments, E:/WorkSpace/ccs_v7/sl_am5728_a15_test/Debug\libsl_am5728_a15_test.a(test.o) does not

      应该是编译静态库时的配置和工程配置（-mfpu）不一致的问题，在网上搜了下，e2e里有个连接：https://community.arm.com/tools/b/blog/posts/arm-cortex-a-processors-and-gcc-command-lines

         根据提示，统一了参数-mfpu=neon-vfpv4之后还是出现上述问题，后来在仔细看了下上述链接，官方建议的编译配置如下：

        -mcpu=cortex-a15 -mfpu=neon-vfpv4 -mfloat-abi=hard

        然而在ccs中，新建工程时只会根据选择的核来指定第一个参数，后两个参数都为空，所以需要根据官网的建议设置好后两个参数。最终，静态库工程的配置和app工程的配置如下：

        -mcpu=cortex-a15 -mtune=cortex-a15 -marm -mfloat-abi=hard -mfpu=neon-vfpv4

        搞定!

        附官网对于-mfloat-abi三种配置的说明：

• -mfloat-abi=soft -- ignore all FPU and NEON instructions, use only the core register set and emulate all floating-point operations using library calls.
• -mfloat-abi=softfp -- use the same calling conventions as -float-abi=soft, but use floating-point and NEON instructions as appropriate. This option is binary compatible with -mfloat-abi=soft and can be used to improve the performance of code that has to conform to a soft-float environment but where it is known that the relevant hardware instructions will be available.
• -mfloat-abi=hard -- use the floating-point and NEON instructions as appropriate and also change the ABI calling conventions in order to generate more efficient function calls; floating-point and vector types can now be passed between functions in the extension registers which not only saves a significant amount of copying but also means that fewer calls need to pass arguments on the stack.