It is a homework . Use a kernel spcae as a char decieve
Which can offer open write and so on.
I just use a char buffer[128] in kernel space.
Then i have some ideas.
I can use kernel space as char device. I can also use kernel spcae as
a file system? Could it be ?
If memory can be a filesystem . Can i use a file to simulate 。
It just not be taken as a file . Like something
we store file in it.
2011/3/13 Gilboa Davara <gilboad@xxxxxxxxx>:
> 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
>
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