Re: [Etherboot-developers] [RFC] Relocation techniques...

[Markus G. <ma...@gu...>]

Eric W. Biederman wrote:
> Technique 1. (Shared library)
> Technique 2. (Virtual Adresses)
> Technique 3. (Fake Relocation)
> 
> So I'm probably going to aim at implementing Virtual Addresses in the
> long term.  If all of the drivers need to be audited for multicast
> support anyway it should be much worse to get a handle on their
> address space operations.

I agree with you, that virtual addresses are the most desirable solution, 
although not neccessarily the easiest one. Whenever this discussion came up in 
the past, I always saw two crucial arguments that ultimately pointed towards 
implementing virtual addresses:

  - code size is crucial. While these days it is relatively common to have at 
least a couple of tens of kilobytes of available ROM space (my original design 
goal for etherboot was to fit into 8kB), there are still enough constraints to 
make it important to carefully manage code size -- especially if you plan on 
making these changes in order to be able to compile multiple drivers into the 
same image.

- the most interesting reason that I could see for this kind of change was the 
prospect that it would allow proper call backs into the driver. Once that is 
possible, there are all kinds of cool things that we can implement.



Markus


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Markus Gutschke
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