Re: reading a file from a module

["Raghu R. Arur" <rra2002@cs.columbia.edu>]

 what does get_fs and set_fs do... i searched for its documnetation and 
cud not get something considerable information... can u pls point me to 
some book or link which explains the basics of these 2 functions...

 thanks,
raghu

On Fri, 8 Nov 2002, Mohit Kalra wrote:

> 
> Your module is a part of the kernel.  Your system call always takes a user
> space string.  when you supply a kernel space string your sys call will
> reject it.
> 
> try using
> 
> fs = get_fs();   // fs is of type mm_segment_t
> set_fs(get_ds())
> 
> /* your code here*/
> 
> set_fs(fs);
> 
> 
> That is, let the sys call consider the kernel space to be a valid source of
> input.  Also look at filp_open if you really want to open a file in kernel
> space.
> 
> Regards,
> Mohit Kalra
> 
> "It is a capital mistake to theorize before one has data.
> Insensibly one begins to twist facts to suit theories, instead of theories
> to suit facts."
> 
> 
> 
> 
>  I am not using the systemcall open(). I am using the sys_open().
> 
>  I create a function pointer of the type sys_open say my_open
> 
>  and do
> 
>  my_open = syscall[__NR_OPEN];
> 
>  and then use it to open the file...
> 
>  But when i do this, i am getting an errno of -14
> which is I suppose illegal operation. So what more do i need to open the
> file from my module.
> 
> 
> 
> 
> 

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