On Wed, 26 Jul 2000 14:49:25 -0400, "Theodore Y. Ts'o" <tytso@MIT.EDU>
wrote:
> Date: Wed, 26 Jul 2000 12:06:49 -0400
> From: Jeff Garzik <jgarzik@mandrakesoft.com>
>
> > Vinay Vernekar wrote:
> > I am developing a network driver which has to read a file
> > 'firmware.bin' and dump it into the modem memory. I want to know how
> > can the file be opened and read inside a driver.
>
> It's much better to do this in userspace as Ted T'so described.
>
> If you must do it in the kernel, just use normal Unix syscalls...
> Inside the kernel, they are called sys_open, sys_read, etc. Make sure
> the code calling those functions doesn't mind if the called functions
> sleep.
>
>I wouldn't recommend that approach at all. First of all, sys_open means
>you're messing with a process's file descriptor table, and if another
>process can get at the fd table (i.e., because of a clone system call),
>they may be able to cause mischief for the kernel (the fd can get
>changed to be something else, etc.). Secondly, sys_read()/sys_write()
>assumes that it will be reading and writing into user memory, not kernel
>memory.
>
>There are games you can play to get around this, but such approaches are
>fragile and complicated, and not what I'd recommend.
How about converting the file into an initialized C structure and then
processing it directly from the driver...
john alvord
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