On Thu, 2011-03-10 at 15:17 +0800, xinyou yan wrote:
I want to and a new syscall
1 add
.long sys_mysyscall
in arch/x86/kernel/syscall_table_32.S
2 add
#define __NR_mysyscall 341
in arch/x86/include/asm/unistd_32.
3. add
asmlinkage int sys_mysyscall(char* sourceFile,char* destFile)
{
int source=sys_open(sourceFile,O_RDONLY,0);
int dest=sys_open(destFile,O_WRONLY|O_CREAT|O_TRUNC,0600);
char buf[1024];
mm_segment_t fs;
fs = get_fs();
set_fs(get_ds());
int nread;
if(source>0 && dest>0)
{
while((nread=sys_read(source,buf,1024)) > 0)
sys_write(dest,buf,read);
}
else
{
printk("Error!");
}
sys_close(source);
sys_close(dest);
set_fs(fs);
return 0;
}
in kerrnel/sys.c
4. make menuconfig
5. make all
6 make modules_install
reboot
Now I want just do it one time
How can i make sure the new syscall here is mysyscall work fine ?
Are you locked on using syscalls?
Unless you really require syscalls, I'd imagine that it's far easier to
use ioctl's instead (doesn't require a custom kernel), and use
filp_open / filp_close / file->read / file->write to access files from
within kernel space.
Two more things:
1. I'd avoid using stack based allocations in kernel mode. (Down to 8KB
in certain situations)
2. Always check error codes.
- Gilboa