编译我自己的内核(不是来自linux-kernel源代码)

Question

我正在学习来自here的内核教程

我在编译我的文件时遇到了问题。

当我尝试编译时，我得到了以下错误：

main.c:8: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:8: error: conflicting types for ‘memcpy’                          
./include/system.h:5: note: previous declaration of ‘memcpy’ was here    
main.c: In function ‘memcpy’:                                            
main.c:12: error: ‘count’ undeclared (first use in this function)        
main.c:12: error: (Each undeclared identifier is reported only once      
main.c:12: error: for each function it appears in.)                      
main.c: At top level:                                                    
main.c:16: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:16: error: conflicting types for ‘memset’
./include/system.h:6: note: previous declaration of ‘memset’ was here
main.c: In function ‘memset’:
main.c:19: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:23: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:23: error: conflicting types for ‘memsetw’
./include/system.h:7: note: previous declaration of ‘memsetw’ was here
main.c: In function ‘memsetw’:
main.c:26: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘strlen’
main.c:49: warning: return type of ‘main’ is not ‘int’
main.c: In function ‘main’:
main.c:64: warning: pointer targets in passing argument 1 of ‘puts’ differ in    signedness
./include/system.h:13: note: expected ‘unsigned char *’ but argument is of type ‘char *’
main.c:51: warning: unused variable ‘i’
scrn.c: In function ‘scroll’:
scrn.c:24: warning: passing argument 1 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘unsigned char *’ but argument is of type ‘short unsigned int *’
scrn.c:24: warning: passing argument 2 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘const unsigned char *’ but argument is of type  ‘short unsigned int *’
scrn.c: In function ‘puts’:
scrn.c:139: warning: pointer targets in passing argument 1 of ‘strlen’ differ in signedness
./include/system.h:8: note: expected ‘const char *’ but argument is of type ‘unsigned char *’

我的文件与本教程中的文件完全相同。

我可以看到，在main.c中，函数的定义如下

void *memcpy(void *dest,const void *src, size_t count)

但在我的system.h文件中，它们的定义如下

extern unsigned char *memcpy(unsigned char *dest,const unsigned char *src, int count)

C不是我的主要语言，但我正在学习它，所以如果我的问题很简单，我很抱歉，但我认为这些定义应该是相同的，不是吗？

Answer 1

您的问题可能是您的平台上的size_t与int不同，或者根本没有正确指定size_t。指针类型应该是OK的(从技术上讲，它们也应该匹配，但在大多数系统上是sizeof(char*) == sizeof(void*))。

如果你正在开发你自己的内核，你会想要写你自己的system.h。如果你同时编写system.h和main.c，你可以让它们以任何你喜欢的方式匹配。如果查看this page of the tutorial，您会看到头文件和C源代码都将memcpy声明为：

unsigned char *memcpy(unsigned char *dest, const unsigned char *src, int count);

但是，如果您在本教程末尾下载示例源文件，您会发现它是：

void *memcpy(void *dest, const void *src, size_t count);

查看该文件的顶部，您会发现以下注释：

/* bkerndev - Bran's Kernel Development Tutorial
*  By:   Brandon F. (friesenb@gmail.com)
*  Desc: Main.c: C code entry.
*
*  Notes: No warranty expressed or implied. Use at own risk. */

看起来您并不是在尝试遵循教程，而是试图从教程中剪切和粘贴代码。这就像是跟着一本书学做脑外科手术一样。你可以让它工作，但如果你不是真的明白你在做什么...好吧，请帮这个世界一个忙，不要把它用在任何批判性的东西上。

Answer 2

在main.c上的每个方法定义中，用int替换size_t