GCC别名功能翻译单元-AKA-的外面是这甚至对工作的工具？ [英] GCC alias to function outside of translation unit -AKA- is this even the right tool for the job?
问题描述
我与FreeRTOS操作系统上的STM32（Cortex-M3的）工作，并使用CMSIS库从ST到引导一切。
I'm working with FreeRTOS on an STM32 (Cortex-M3), and using the CMSIS library from ST to bootstrap everything.
该CMSIS库定义弱符号 SVC_HANDLER 在启动.S文件。它必须在某个地方为了得到你的ISR在中断向量表覆盖。 FreeRTOS的定义 vPortSVCHandler ，这是我想有处理SVC中断的ISR。
The CMSIS library defines the weak symbol SVC_Handler in the startup ".s" file. It must be overridden somewhere in order to get your ISR in the interrupt vector table. FreeRTOS defines vPortSVCHandler, which is the ISR I want to have handle the SVC interrupt.
我想胶水两个一起用我的应用程序code（即W / O modifyng FreeRTOS操作系统或CMSIS源$ C $ C）。我认为一个别名将是工作的工具，所以我想这（在一个单独的源文件，main.c中）：
I would like to "glue" the two together using my application code (i.e. w/o modifyng FreeRTOS or the CMSIS source code). I thought an alias would be the right tool for the job, so I tried this (in a separate source file, main.c):
void SVC_Handler(void) __attribute__ ((alias ("vPortSVCHandler")));
这会导致：错误：'SVC_HANDLER别名为未定义的符号vPortSVCHandler
原来，根据这里 HTTP GCC文档：//gcc.gnu。组织/ onlinedocs / GCC /功能-Attributes.html ，为了使用别名属性，你不能别名翻译单元之外的象征。所以，我想我会尝试的extern 符号到main.c中，像这样：
Turns out, according to GCC documentation here http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html, in order to use the alias attribute, you cannot alias a symbol outside of the translation unit. So I thought I'd try to extern the symbol into main.c like so:
extern void vPortSVCHandler( void ) __attribute__ (( naked ));
void SVC_Handler(void) __attribute__ ((alias ("vPortSVCHandler")));
这会产生同样的错误。任何建议???
This generates the same error. Any suggestions???
我真的想避免修改要么库。我知道我可以写一个函数 SVC_HANDLER ，简单地调用 vPortSVCHandler ，但可能的不必要开销的ISR增加（可能取决于优化设置）。注：FreeRTOS的例子通过自定义启动文件做到这一点。我正在寻找一种方法来从C的或做的我的链接脚本。
I would really like to avoid modifying either of the libraries. I know I could write a function SVC_Handler that simply calls vPortSVCHandler, but that could add unnecessary overhead to the ISR (possibly depending on optimization settings). Note: The FreeRTOS examples accomplish this via a custom startup file. I'm looking for a way to do this from C or my linker script.
- 编译器版本：gcc版本4.5.2（的Sourcery G ++精简版2011.03-42）
- 目标：手臂无-EABI
推荐答案
您应该能够要么链接脚本，或者通过相应的选项来连接器，如要做到这一点。为LD， - defsym = SVC_HANDLER = vPortSVCHandler
You should be able to do this either with a linker script, or by passing the appropriate option to the linker, eg. for ld, --defsym=SVC_Handler=vPortSVCHandler
请参阅Binutils的文档的LD <获得更多的信息href=\"http://sourceware.org/binutils/docs-2.21/ld/Options.html#index-g_t_002d_002ddefsym_003d_0040var_007bsymbol_007d_003d_0040var_007bexp_007d-163\"><$c$c>--defsym选项，<一href=\"http://sourceware.org/binutils/docs-2.21/ld/Simple-Assignments.html#Simple-Assignments\">assignments在链接脚本
See the binutils documentation for more information on the ld --defsym option, and assignments in linker scripts
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