Re: Kernel Ioctl

[Babu Rajagopal <rbabs@yahoo.com>]

Hi,

Actually IOCTL provides a entrypoint for your driver.
read, write are other entry points.
these entry points can be used for any purposes. but
as a convention, IOCTL is used for configuring the
device. 

 --- Dan Erickson <coldoneknight@rogers.com> wrote: > 
> 	Recently I had some help from somebody on the
> openprojects irc 
> server in channel #kernelnewbies.
> 	I was asking how ioctl works and what not, and was
> extremely 
> confussed. My purpose of this letter is to ask some
> questions, but to also 
> make sure my understanding of it is correct and not
> false.
> So... I will start off my showing an example which I
> grabbed from the 
> kernel source for the pci watchdog (wdt_pci.c). This
> is just one of the 
> options the card supports.
> 
> case WDIOC_KEEPALIVE:
>        wdtpci_ping();
>        return 0;
> 
> So basicly wdtpci_ping() is the code for
> WDIOC_KEEPALIVE.
> (What to do when WDIOC_KEEPALIVE is called).
> (is my thinking on this correct?)
> 
> I asked the person I was talking to on
> #kernelnewbies what sends the 
> command? ie) the unsigned int cmd in ioctl.
> And he said a userspace program sends the command.
> Is this true?
> What I mean, is that something needs to say "I want
> to keep the computer 
> alive". So I will call WDIOC_KEEPALIVE to do this
> for me. And it was 
> highly confussing me as to what actualy sends the
> WDIOC_KEEPALIVE to the 
> driver.
> 
> 	Could somebody please clear this up for me?
> 
> 
> Thanks alot
> 
> -Dan Erickson-
> -ColdOneKnight@rogers.com-
> 
> 
> 
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> Kernelnewbies: Help each other learn about the Linux
> kernel.
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