问题

我想在Cortex M4微控制器中运行一个简单的Hello World代码。（Nuvoton M487KM）
所有的工具、板支持文件和IDE都在网站上提供，并且与Eclipse IDE（NuEclipse GCC Windows）一起安装。
创建一个基本的Hello World项目后，我尝试构建项目，但不断收到这些错误，无法停止困扰我。

以下是代码：（main.c）

#include <stdio.h>
#include "NuMicro.h"

#define PLL_CLOCK           192000000

void SYS_Init(void)
{
    /*---------------------------------------------------------------------------------------------------------*/
    /* Init System Clock                                                                                       */
    /*---------------------------------------------------------------------------------------------------------*/
    /* Unlock protected registers */
    SYS_UnlockReg();

    /* Set XT1_OUT(PF.2) and XT1_IN(PF.3) to input mode */
    PF->MODE &= ~(GPIO_MODE_MODE2_Msk | GPIO_MODE_MODE3_Msk);

    /* Enable External XTAL (4~24 MHz) */
    CLK_EnableXtalRC(CLK_PWRCTL_HXTEN_Msk);

    /* Waiting for 12MHz clock ready */
    CLK_WaitClockReady(CLK_STATUS_HXTSTB_Msk);

    /* Set core clock as PLL_CLOCK from PLL */
    CLK_SetCoreClock(PLL_CLOCK);
    /* Set PCLK0/PCLK1 to HCLK/2 */
    CLK->PCLKDIV = (CLK_PCLKDIV_APB0DIV_DIV2 | CLK_PCLKDIV_APB1DIV_DIV2);

    /* Enable UART clock */
    CLK_EnableModuleClock(UART0_MODULE);

    /* Select UART clock source from HXT */
    CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UART0SEL_HXT, CLK_CLKDIV0_UART0(1));

    /* Update System Core Clock */
    /* User can use SystemCoreClockUpdate() to calculate SystemCoreClock. */
    SystemCoreClockUpdate();

    /* Set GPB multi-function pins for UART0 RXD and TXD */
    SYS->GPB_MFPH &= ~(SYS_GPB_MFPH_PB12MFP_Msk | SYS_GPB_MFPH_PB13MFP_Msk);
    SYS->GPB_MFPH |= (SYS_GPB_MFPH_PB12MFP_UART0_RXD | SYS_GPB_MFPH_PB13MFP_UART0_TXD);
    /* Lock protected registers */
    SYS_LockReg();
}

/*
 * This is a template project for M480 series MCU. Users could based on this project to create their
 * own application without worry about the IAR/Keil project settings.
 *
 * This template application uses external crystal as HCLK source and configures UART0 to print out
 * "Hello World", users may need to do extra system configuration based on their system design.
 */

int main()
{
    SYS_Init();
    /* Init UART to 115200-8n1 for print message */
    UART_Open(UART0, 115200);
    /* Connect UART to PC, and open a terminal tool to receive following message */
    printf("Hello World\n");

    /* Got no where to go, just loop forever */
    while(1);
}

以下是我得到的错误：

c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-closer.o): in function `_close_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-fstatr.o): in function `_fstat_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-isattyr.o): in function `_isatty_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-lseekr.o): in function `_lseek_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-readr.o): in function `_read_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-sbrkr.o): in function `_sbrk_r':	hellowork		 	C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-writer.o): in function `_write_r':	hellowork		 	C/C++ Problem
make: *** [hellowork.elf] Error 1	hellowork		 	C/C++ Problem
recipe for target 'hellowork.elf' failed	makefile	/hellowork/Debug	line 56	C/C++ Problem
undefined reference to `_close'	hellowork		line 0	C/C++ Problem
undefined reference to `_fstat'	hellowork		line 0	C/C++ Problem
undefined reference to `_isatty'	hellowork		line 0	C/C++ Problem
undefined reference to `_lseek'	hellowork		line 0	C/C++ Problem
undefined reference to `_read'	hellowork		line 0	C/C++ Problem
undefined reference to `_write'	hellowork		line 0	C/C++ Problem
undefined reference to `errno'	hellowork		line 0	C/C++ Problem
undefined reference to `errno'	hellowork		line 0, external location: c:\program files (x86)\gnu arm embedded toolchain 2021.10\arm-none-eabi\bin\ld.exe: closer.c	C/C++ Problem
undefined reference to `errno'	hellowork		line 0, external location: c:\program files (x86)\gnu arm

<details>
<summary>英文:</summary>

I want to dump a simple Hello World code in a Cortex M4 microcontroller.(Nuvoton [M487KM](https://www.nuvoton.com/export/resource-files/UM_NuMaker-M487KM_User_Manual_EN_Rev1.00.pdf))
All the tool, board support files and IDE are provided on the [website](https://www.nuvoton.com/board/numaker-pfm-m487km/?index=2) which are installed with the Eclipse IDE (NuEclipse GCC Windows).
After creating a basic Hello world project, I try to build the project but keep getting these errors that wont stop bothering me.


Here is the code: (main.c)

#include <stdio.h>
#include "NuMicro.h"

#define PLL_CLOCK 192000000

void SYS_Init(void)
{
/---------------------------------------------------------------------------------------------------------/
/* Init System Clock /
/---------------------------------------------------------------------------------------------------------/
/ Unlock protected registers */
SYS_UnlockReg();

/* Set XT1_OUT(PF.2) and XT1_IN(PF.3) to input mode */
PF-&gt;MODE &amp;= ~(GPIO_MODE_MODE2_Msk | GPIO_MODE_MODE3_Msk);

/* Enable External XTAL (4~24 MHz) */
CLK_EnableXtalRC(CLK_PWRCTL_HXTEN_Msk);

/* Waiting for 12MHz clock ready */
CLK_WaitClockReady(CLK_STATUS_HXTSTB_Msk);

/* Set core clock as PLL_CLOCK from PLL */
CLK_SetCoreClock(PLL_CLOCK);
/* Set PCLK0/PCLK1 to HCLK/2 */
CLK-&gt;PCLKDIV = (CLK_PCLKDIV_APB0DIV_DIV2 | CLK_PCLKDIV_APB1DIV_DIV2);

/* Enable UART clock */
CLK_EnableModuleClock(UART0_MODULE);

/* Select UART clock source from HXT */
CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UART0SEL_HXT, CLK_CLKDIV0_UART0(1));

/* Update System Core Clock */
/* User can use SystemCoreClockUpdate() to calculate SystemCoreClock. */
SystemCoreClockUpdate();



/* Set GPB multi-function pins for UART0 RXD and TXD */
SYS-&gt;GPB_MFPH &amp;= ~(SYS_GPB_MFPH_PB12MFP_Msk | SYS_GPB_MFPH_PB13MFP_Msk);
SYS-&gt;GPB_MFPH |= (SYS_GPB_MFPH_PB12MFP_UART0_RXD | SYS_GPB_MFPH_PB13MFP_UART0_TXD);
/* Lock protected registers */
SYS_LockReg();

}

This is a template project for M480 series MCU. Users could based on this project to create their
own application without worry about the IAR/Keil project settings.
*
This template application uses external crystal as HCLK source and configures UART0 to print out
"Hello World", users may need to do extra system configuration based on their system design.
*/

int main()
{

SYS_Init();
/* Init UART to 115200-8n1 for print message */
UART_Open(UART0, 115200);
/* Connect UART to PC, and open a terminal tool to receive following message */
printf(&quot;Hello World\n&quot;);

/* Got no where to go, just loop forever */
while(1);

}




 And these are the errors I get:

c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-closer.o): in function _close_r': hellowork C/C++ Problem c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-fstatr.o): in function_fstat_r': hellowork C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-isattyr.o): in function _isatty_r': hellowork C/C++ Problem c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-lseekr.o): in function_lseek_r': hellowork C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-readr.o): in function _read_r': hellowork C/C++ Problem c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-sbrkr.o): in function_sbrk_r': hellowork C/C++ Problem
c:/program files (x86)/gnu arm embedded toolchain/10 2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp\libc_nano.a(lib_a-writer.o): in function `_write_r': hellowork C/C++ Problem
make: *** [hellowork.elf] Error 1 hellowork C/C++ Problem
recipe for target 'hellowork.elf' failed makefile /hellowork/Debug line 56 C/C++

Problem
undefined reference to _close' hellowork line 0 C/C++ Problem undefined reference to_fstat' hellowork line 0 C/C++ Problem
undefined reference to _isatty' hellowork line 0 C/C++ Problem undefined reference to_lseek' hellowork line 0 C/C++ Problem
undefined reference to _read' hellowork line 0 C/C++ Problem undefined reference to_write' hellowork line 0 C/C++ Problem
undefined reference to errno' hellowork line 0 C/C++ Problem undefined reference toerrno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: closer.c C/C++ Problem
undefined reference to errno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: fstatr.c C/C++ Problem undefined reference toerrno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: isattyr.c C/C++ Problem
undefined reference to errno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: lseekr.c C/C++ Problem undefined reference toerrno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: readr.c C/C++ Problem
undefined reference to `errno' hellowork line 0, external location: c:\program files (x86)\gnu arm embedded toolchain\10 2021.10\arm-none-eabi\bin\ld.exe: writer.c C/C++ Problem



According to the NuEclipse [User Manual](https://www.nuvoton.com/resource-files/UM_NuEclipse_EN_Rev1.01.014.pdf), we need to set global Toolchain Settings which I did.
The path to Toolchain and Build tools is also mentioned.
Still the code keeps giving me these errors. I read online that it might be the &quot;libc_nano.a&quot; files issue but the those solutions have not helped me.
Can someone please help me!!

</details>


# 答案1
**得分**: 1

看起来您正在使用Newlib C库，需要提供_syscalls_存根来将库与您的硬件/运行时环境配合使用。

许多存根只需要虚拟实现。要支持`printf`，您需要实现`_write_r()`。要支持堆（`malloc()`等），您需要实现`_sbrk_r`。

需要实现的系统调用的详细信息可以在https://sourceware.org/newlib/libc.html#Reentrant-Syscalls找到，并在https://sourceware.org/newlib/libc.html#Stubs中找到“最小”实现示例。请注意，如果您不使用多线程或需要非常简单的实现，可重入版本可以简单地映射到（或以相同方式实现为）非可重入版本。 `_r`变体允许使用线程特定的`errno`，例如。

您只需创建一个包含这些函数实现的源文件，并将它们链接到您的项目中以解决链接问题。看起来您的工具链已经在这些文件中提供了支持：

```none
closer.c
fstatr.c
isattyr.c
lseekr.c
readr.c 
writer.c

这些是需要修改、重新实现或可能已经OK的文件，但您需要提供由链接器错误指示的errno支持（一个全局变量）。在多线程环境中，errno需要根据线程进行“切换”（最好是这样，或者根本不依赖于errno），但除此之外，大多数情况下只需要一个全局变量（也如https://sourceware.org/newlib/libc.html#Stubs中所述）。

英文:

It looks like you are using the Newlib C library for which you need to provide the syscalls stubs to couple the library to your hardware/runtime environment.

Many of the stubs only need dummy implementations. To support printf you need to implement _write_r(). To support a heap (malloc() et al), you need to implement _sbrk_r.

Details of the syscalls that need implementing can be found at https://sourceware.org/newlib/libc.html#Reentrant-Syscalls, along with "minimal" implementation examples at https://sourceware.org/newlib/libc.html#Stubs. Noting that the re-entrant versions can simply map to (or be implemented in teh sae way as) the non-reentrant versions if you are not multi-threading or for very simple implementations. The _r variants allow for a thread specific errno for example.

You simply need to create a source file with these functions implemented and link them to your project to resolve the links. It looks like your tool chain already provides for this in these files:

closer.c
fstatr.c
isattyr.c
lseekr.c
readr.c 
writer.c

Those are the ones that need modifying, reimplementing or possibly they are ok, but you need to provide the errno support (a global) indicated by the linker error. In a multi-threaded environment errno needs "switching" per thread (ideally - or just never rely on errno), but otherwise a single global is all that is needed most likely (also as described at https://sourceware.org/newlib/libc.html#Stubs).

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