Re: Using GNAT in Linux kernel modules, was: Re: Free RTOS with support for Ada ?

[gerhard.nospam@bigfoot.de (Gerhard Häring)]

>I was also aware (from the Ada Linux Programming book from
>www.adapower.com) that you need to use a pragma to disable the Ada runtime
>when doing Linux kernel modules.
>
>However, this book does not cover kernel programming in any detail and the
>GNAT reference manual just refers you to the GNORT documentation, which does
>not appear to be publically available, so I had dismissed this as an option.
>
>However, since this option is mentioned above, I wonder if I have missed
>something.
>
>Has anybody successfully implemented a Linux/RTlinux kernel module in Ada
>using just the public GNAT and freely available documentation and what problems
>did you have ?

FWIW, I have once implemented a toy Linux kernel module with the publicly
available version of GNAT. I also started to port a relatively simple Linux
kernel module to Ada (the driver for the bttv video cards).

I can tell you that it's possible. But for me, it was quite frustrating,
because I had to "fake" C a lot, I couldn't get rid of C completely because the
Linux kernel uses lots of #defines and you have to wrap these at least to Ada
functions/procedures.

It would be nice if the complete Linux kernel API were available as an Ada
binding, but this would be a tremendous effort and would have to be updated for
every new kernel version. Not quite realistic. I have only translated the C
stuff on a as-needed basis.

Wrt to the PRAGMA No_Run_Time, it wasn't available with GNAT 3.12p and I could
do without. I still don't quite get the point of it: it still lets you use
features that need the Ada runtime.

Gerhard

PS: You can't allocate stuff on the heap. (Part of) The GNAT runtime would need
to be ported to the Linux kernel environment, so that it uses kmalloc instead
of the C library's malloc.
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