----- Original Message -----
From: "Nathan Paul Simons" <[EMAIL PROTECTED]>
To: "Norm Dresner" <[EMAIL PROTECTED]>
Cc: "Raul" <[EMAIL PROTECTED]>; "Real Time Linux" <[EMAIL PROTECTED]>
Sent: Monday, January 29, 2001 2:59 PM
Subject: Re: [rtl] shared memory for functions
> Actually, you could implement a function that does not reference any
> external symbols (eg, most common is printf() from libc) in user-space,
then
> send the address of the function to an RTLinux thread so that it can be
called
> from RTLinux space as well. This is actually what we do in RTLinux for
PSC
> (our user-level real-time threads support).
Excuse me for butting in, but how would this work? What happens when the
user-space task dies or is terminated between passing the address of the
function to the RT task and its calling the function? Isn't the user-space
address illegal as far as the RT task is concerned (unless you share it)?
Rich Cloutier
> Just note that you can't
> (currently) make syscalls from kernel or RTLinux. We are still looking at
> this for PSC. See the psc/ directory in RTLinux for more details.
>
> On Mon, Jan 29, 2001 at 10:49:27AM -0500, Norm Dresner wrote:
> > AFAIK the only way to access functions that exist in kernel space is via
> > explicit calls to a "device driver" which could be read/write but are
much
> > more commonly done via the standard ioctl(2) mechanism. There simply is
no
> > way to directly "call" such a function because the kernel is not in the
> > address space of any user task.
> > Norm
> >
> > ----- Original Message -----
> > From: Raul <[EMAIL PROTECTED]>
> > To: Real Time Linux <[EMAIL PROTECTED]>
> > Sent: Monday, January 29, 2001 7:14 AM
> > Subject: [rtl] shared memory for functions
> >
> >
> > > Hi
> > > I have some functions that get called by programs that
> > > run both in user-space and rtl-space.
> > > Would it be possible to declare these functions only
> > > once and use shared memory so that the programs can
> > > access them? If it is possible what happens with the
> > > parameters sent to this funcitons? Is there any
> > > example?
> > > Thank you in advance,
> > > Raul
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>
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