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From: "q.kontinuum" <achsis_of_elvis@yahoo.co.uk>
Newsgroups: comp.lang.ada
Subject: Re: Linux kernel module - memory allocation
Date: Mon, 18 May 2015 09:19:05 +0000 (UTC)
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Date: 2015-05-18T09:19:05+00:00
List-Id: <comp.lang.ada>

Hi, thanks a lot for the fast reply.

In comp.lang.ada, you wrote:
> On 15-05-18 11:27 , q.kontinuum wrote:
> Do you mean a real "driver", either kernel-linked or a loadable module? 

Yes, I'm aiming for a loadable kernel module.

> Which Ada compiler are you using? Do you use some specific compiler 
> switches to adapt it to the driver environment?

I'm using gnat. Command line to compile a 
gnatmake -a -s -mcmodel=kernel ...

> But GNAT can also translate some C headers into Ada 
> declarations automatically.

I should look into that. Good to know.

> You could try with a constrained string subtype, say String(1 .. 10), 

I assume if I use that within a function, I'd run into the same problem
because the function might be called more often, thus still requiring
dynamic allocation. Since I know that only one instance of the driver 
will be used single threaded, and only one buffer is used, I could 
declare it in the modules declaration section rather than the function.

> what you should use. Perhaps you can wrap it up as a user-defined Ada 
> "storage pool" (see the Ada RM 13.11) which would let you use the "new" 
> statement

This sounds like just what I need - I will definitely have a closer look
at it, thanks a bunch!

> or you can write an Ada binding in the same way as for your C 
> wrappers. kmalloc seems to return a C "void *". Assuming that this is 
> implemented as an address, you should be able to use the predefined Ada 
> package System.Address_To_Access_Conversions to convert the kmalloc 
> result to a pointer of any type you want (but beware memory alignment 
> errors -- the documentation for kmalloc that I found did not promise to 
> return memory aligned in any particular way).

Thanks, sounds like a good starting point to gather some further 
information myself.