Re: RFC: PPP over X

["Andi Kleen" <ak@xxxxxxx>]

On Thu, Feb 10, 2000 at 09:26:28AM -0600, Dave Grothe wrote:
> Matti Aarnio wrote:
> 
> > On Thu, Feb 10, 2000 at 08:36:13AM -0600, Dave Grothe wrote:
> >  Without making a
> > > trip up to user space the answer always has to be "can't be done."  The
> > > reason being that we can't configure our SNA code (STREAMS based) above
> > > TCP while keeping the messages in the kernel.
> >
> >         Yes you can.  You can "simulate" user dataspace in kernel
> >         by doing:
> >
> >         (from mm/filemap.c)
> 
> This looks like a technique for writing to any old file system from inside the
> kernel.  What about the other direction.  Do you have to set up a kernel 
> thread per
> data stream and use a similar technique to "read" from the file system?  Or 
> maybe one
> could concoct an inside-the-kernel kludge to use poll().

You need a kernel thread to read/write TCP or UDP, because their socket
layer requires process context. e.g. sunrpc does it this way for asynchronous
NFS.


Have a nice vacation,
-Andi