Yocto Raspberry Pi - 安装 rpi_ws281x 库时出错

Question

我正在尝试使用 Yocto Project 构建最小的树莓派零映像。我对 C 不熟悉，但我想知道为什么在编译“ws2811.c”期间会出现这个（微不足道的）错误，我可以在另一个带有 raspbian OS 的 raspberry pi 2 上成功构建（整个库）而没有任何错误。感谢您的每一个提示和帮助！

存储库：

https://github.com/jgarff/rpi_ws281x

我的配方在尝试构建根（存储库）位置“scons”时卡住了：

sudo scons

Bitbake 编译配方任务输出：

| DEBUG: Executing python function externalsrc_compile_prefunc
| NOTE: python-ws2812: compiling from external source tree /home/astor/Documents/poky/rpi-build/workspace/sources/python-ws2812
| DEBUG: Python function externalsrc_compile_prefunc finished
| DEBUG: Executing shell function do_compile
| scons: Reading SConscript files ...
| scons: done reading SConscript files.
| scons: Building targets ...
| CC      ws2811.o
| ws2811.c: In function 'setup_pwm':
| ws2811.c:289:23: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
|      dma_cb->dest_ad = (uint32_t)&((pwm_t *)PWM_PERIPH_PHYS)->fif1;
|                        ^
| cc1: all warnings being treated as errors
| scons: *** [ws2811.o] Error 1
| scons: building terminated because of errors.
| WARNING: /home/astor/Documents/poky/rpi-build/tmp/work/arm1176jzfshf-vfp-poky-linux-gnueabi/python-ws2812/1.0+git999-r0/temp/run.do_compile.11838:1 exit 2 from 'scons'
| ERROR: Function failed: do_compile (log file is located at /home/astor/Documents/poky/rpi-build/tmp/work/arm1176jzfshf-vfp-poky-linux-gnueabi/python-ws2812/1.0+git999-r0/temp/log.do_compile.11838)

这看起来像我的食谱：

LICENSE = "BSD"
LIC_FILES_CHKSUM = "file://LICENSE;md5=9dcf340793a1d73c5211edc8238767dc"

SRC_URI = "git://github.com/richardghirst/rpi_ws281x.git;protocol=https"

PV = "1.0+git${SRCPV}"
SRCREV = "39afaac5f2b8b307d7d7b5f2f790fbb6759bda5e"

S = "${WORKDIR}/git"

DEPENDS = "swig-native"

inherit scons setuptools 

do_compile_prepend() {
    cd ${S}/
    scons
    ${PYTHON} ${S}/python/setup.py install
}

Answer 1

dma_cb->dest_ad = (uint32_t)&((pwm_t *)PWM_PERIPH_PHYS)->fif1;

这似乎完全符合错误所说的：将指针转换为 32 位整数。当指针是 64 位时，这是不安全的。

您可以通过额外的强制转换（首先转换为足够大的整数）或确保使用-Wno-pointer-to-int-cast 来消除警告。但这几乎肯定是个坏主意：地址应该存储为指针，而不是 32 位整数。

至于编译在其他地方成功的原因：我假设 raspbian 是一个 32 位操作系统（至少在 pi2 上），所以指针恰好是正确的大小。

这当然会导致另一种解决方法：您可以构建一个 32 位的 yocto 映像。这不会使代码正确，但至少错误会消失:)