Re: intercommunications between Linux kernel modules

[david]

On Thu, 6 Oct 2011, Cyclonus J wrote:

> On Thu, Oct 6, 2011 at 7:04 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
> > Cyclonus J <cyclonusj@xxxxxxxxx> writes:
> >
> > > I am looking for a way to do an IPC-like communications between two
> > > linux kernel modules, such as mqueue or shared memory. After searching
> > > for a while, I can't find such information available inside existing
> > > linux kernel or online.
> > >
> > > So, my question is if this is something discussed before here and gets
> > > rejected or still might be accepted in the mainstream kernel tree?
> >
> > All kernel memory is shared in Linux, so the concept doesn't make sense.
> >
> > If you want to send messages or communicate inside the kernel there are
> > lots of different facilities available.
>
> Andi,
>
> That would be great! Could you point me to some facilities that can do
> this message passing between kernels?

what you are missing is that there aren't two different kernels. it's one 
big process. think multi-threaded programming instead of inter-process 
communication. You don't even have well defined threads to work with so 
you can't say "I'm in thread 1 and need to communicate with thread 2", you 
need to think "I'm in this routine and I need to set a message in a way 
that another routine will read it", this can be as simple as just setting 
a variable (although you do need to make it the equivalent of 'thread 
safe' through appropriate locking or lock-free protection)

David Lang
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