Re: PPMC & rtlinux

[Paul Corner <paul.corner-at-tesco.net>]

Hi Jon


On Mon, 11 Dec 2000, Jon Elson wrote:
> But, I can see some possible ways TkEMC could cause real trouble.
> Probably the biggest one (Ray, you know more about this than
> anyone) is something to do with the process of initializing variables
> in the RT task.  If anything in TkEMC scrambles the mechanism
> that hands those variables across the shared memory, they could
> literally trash any location in physical memory, by causing a wild
> pointer in the RT task.  Now, this is a real stretch, since the
> routines that accept these messages are pretty well put together.
> On another tack, is there anything in the TCL interpreter and
> its interface to the GUI that might be affected by a break in
> program continuity? 

As I understand it, for later versions of rtlinux, the message handling is
no longer done through shared memory. On the 2.2.13-rtl2.0 kernel, I don't
have any shared memory set aside. An advantage at present, as the hard disk is
being swapped between a couple of machines with differing amounts of memory.

I cannot get the current CVS source to build on any kernel/rtl combinations at
present. But I would assume that later kernels no longer require the shared
memory.

Regards, Paul.