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Re: physmem, simple containers

From: Marcus Brinkmann
Subject: Re: physmem, simple containers
Date: Tue, 27 Jan 2004 17:14:35 +0100
User-agent: Mutt/1.5.4i

On Tue, Jan 27, 2004 at 05:05:44PM +0100, Niels Möller wrote:
> A practical matter, is it possible to link an object file into wortel
> and have it be automatically page aligned and put into it's own page?
> Startup code can be a single page mapped read-only into all started
> tasks. Startup data must be separate for each task, though. (Ideally,
> the startup data page should somehow be returned to physmem when the
> task is up and running).

I am not talking about the bootstrap case now, but please consider it:
Normally, the startup page must be allocated on behalf of the newly created
task and then granted (not mapped) into its address space.  This is because
in the suid case, the filesystem can not be bothered to keep track of it, it
should be deallocated (if ever) by the child.

For the bootstrap case, physmem can give wortel such a page allocated for
the child, along with the container cap, etc.  I think this was what I wanted
to do.

I wanted to put data and code into a single page, if it fits.  Copying it is
no problem at all!

BTW, the answer to your question seems to be no, IIRC.  You can only do that
if you align sections in the ELF file, or so.  I remember playing with this
for the device archive module for deva (which is based on ELF, and has
exactly the alignment requirement you talk about), and it was quite hard.


`Rhubarb is no Egyptian god.' GNU      http://www.gnu.org    address@hidden
Marcus Brinkmann              The Hurd http://www.gnu.org/software/hurd/

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