编译我自己的内核（不是来自linux内核源代码）

Question

I'm following the kernel tutorial from here

im having problems compiling my files.

i get the following errors when i try to compile:

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 *’

My files are exact copies of the ones from the tutorial.
I can see that in main.c the functions are defined like so

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

but in my system.h file they are defined like so

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

C is not my primary language but i am in the process of learning it so I apologize if my question is simple but I would think that these definitions should be the same not?

Answer 1

Probably your issue is that size_t isn't the same as int on your platform, or size_t isn't specified correctly at all. The pointer types should be OK (technically, they should match too, but on most systems sizeof(char*) == sizeof(void*) ).

If you're developing your own kernel, you'd want to write your own system.h . If you're writing both system.h and main.c , you can make them match up however you'd like. If you look at this page of the tutorial , you'd see that header and C source both declare memcpy as:

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

But if you download the example source files at the end of the tutorial, you find it is instead:

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

Looking at the top of that file, you find the following comment:

/* 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. */

It doesn't look like you're trying to follow a tutorial, but rather that you're trying to cut and paste code from a tutorial. That's like trying to learn to perform brain surgery by following along in a book. You might get it to work, but if you don't really understand what you're doing... well, please do the world a favor and don't use it for anything critical.

Answer 2

在main.c上的每个方法定义中用size替换size_t