Re: [NILO-discuss] Zen and the art of running in real mode

[Marty C. <md...@en...>]

On Mar 8, 2005, at 1:10 PM, H. Peter Anvin wrote:
> Marty Connor wrote:
>> Drivers we can fix.  Older ones are probably simpler anyway, and 
>> newer ones probably use inX/outX already.
> Not all drivers *can* be modified to use in/out (i.e. portio) as 
> opposed to read/write (i.e. MMIO.)  It's a function of the hardware.

Drat.  Hopefully these represent old, rarer, and hopefully less-used 
cards.

>> If you say so :)  Sounds like a somewhat fragile hack, but sometimes 
>> that's all we've got that gets the job done.
> It's not fragile, you just have to put the proper entry point code at 
> both the 16- and the 32-bit entry point.

I have faith.  I hope someday to have better understanding. :)

>>> I appreciate that all this is quite involved, so I'm going to 
>>> attempt a
>>> brief summary:
>>> o  We can support genuine real-mode operation, V86-mode operation 
>>> and the
>>>    PXE-specified 16-bit protected-mode operation.
>>> o  Doing this gives us compatibility with FreeBSD and with any
>>>    as-yet-undiscovered program that uses the PM entry point.
>> Are things that do this "broken" or "violating the spec" somehow?
>> What I'm getting at, is how hard we should try to get people to fix 
>> their code to work with ours?  I can already hear comments like "well 
>> it works with my Intel boot ROM on my eepro100... and also with my 
>> 3C905 MBA Boot ROM..."   It would be nice to have some good reasons 
>> why they should fix it.
> Perhaps the first thing to do is to print a legible message if 
> something tries to call the PM entry point and/or invoke the RM entry 
> point in V86 mode.  Something asking them to report what they're 
> trying to do, and we could evaluate the importance at that point.

Yes, hopefully we can use rom-o-matic.net to encourage people to report 
their experiences in such a way that they are useful.

Hmmm, a convenient web form offering a free iPod mini and a private 
introduction to the Coors twins comes to mind, but maybe we can appeal 
to their more altruistic natures :)

This is exciting conversation (read: I need to get out more :)  I can't 
wait until we have something to document and test.

In order to move things along, I've asked Michael to import code into 
the nilo tree whenever he is ready, setting a tag in the Etherboot 
tree.

I'm expecting there will be a fair bit of heavy demolition once the 
low-level interface issues are in place.  Hopefully at that point more 
people will join in the discussion, and maybe help with the hacking.

To those quietly lurking: Don't be shy if you have an idea or opinion 
-- share it!

Marty