Re: Linux Calls

[David Holm <david@realityrift.com>]

On 31 Jul 2003 20:26:17 +0100
Simon Wright <simon@pushface.org> wrote:

> "Jeremy Smith" <jeremy.t.smith@mindspring.com> writes:
> 
> > I have two tasks, built using gnat 3.13p, running under Linux, Red Hat 8.
> > The idea was to have one task processing and performing cyclic tasks
> > continuously while the other task waits for commands and responds to them
> > right away.  To accomplish this I am want to run the command receipt task at
> > a higher priority than the continuous processing task.  My problem is that
> > the commands are coming over an IPC message queue, so when the command
> > receipt task calls msgget (visible via pragma Import) it blocks but does it
> > outside the Ada RTS.  The continuous processing task never gains context
> > because the Ada RTS doesn't know the command receipt task has blocked
> > pending receipt of the next command.
> > 
> > Anybody know a way to wrap a blocking OS call so that the other lower
> > priority Ada tasks can play until it returns?
> 
> It sounds as though you're using the "fsu" version of the runtime
> system - you need the version that uses native threads. On recent
> editions of GNAT, & I'm pretty sure on 3.13p, you get a choice between
> fsu & native; check out the installation instructions. (as far as I
> can remember, it involves switching the symlinks for adainclude,
> adalib in ...lib/gcc-lib/i686-pc-linux-gnu/2.8.1/ .
> 
> The binary I have is called gnat-3.13p-i686-pc-linux-gnu-bin.tar.gz

At least with 3.14p and 3.15p you can select the run-time system with --RTS=fsu/native when you
call gnatmake och gnatgcc.

//David Holm