Re: Patch to align virt and phys spaces on i386

On Mar 9, 2006, at 6:42 PM, Glenn Brown wrote:
> Could you briefly explain the motivation for KEEP_IT_REAL?  
> Specifically, what's the down side of not supporting it, what's it  
> for other than strict PXE compliance, how does it relate to EFI now  
> that Intel claims EFI has superceded PXE, and where can I get a  
> copy of the PXE spec now that Intel no longer distributes it?

I put a copy of the PXE spec at:

     http://etherboot.org/ref/pxespec.pdf

You can get a copy of the EFI spec at:

     http://www.uefi.org/index.php?pg=4

The PXE doc is so old, I don't think anybody cares if we give out  
copies, but the EFI people are still in active development, and they  
want to control distribution of the spec.  It's 1500 pages, and looks  
like it was written by ex-DEC documentation people, as it is very  
detailed.

I'm very interested in hearing what Michael and hpa think of it,  
since they have a lot of familiarity with the PXE spec. (suffice it  
to say that the PXE spec was, umm, kind of lame).

> > I'd prefer to keep it down to
> > just one mechanism for simplicity.

> I'm inclined to choose mechanism over policy.  I concede it invites  
> the "broken window phenomenon" as far as KEEP_IT_REAL is concerned,  
> and will attempted to mitigate that with stategically placed  
> warnings in our myri10ge.c driver.  I think driver writers should  
> have a[n informed] choice; but I'm biased, of course, since I have  
> a working and fully tested driver with the 4KB relocate.patch, and  
> there appears to be no benefit to our driver of using a different  
> alignment strategy.

This is the soup we swim in.  It'll be interesting how to figure out  
how to follow specs and still support real hardware, but it comes  
with the territory.

I want to get a fancy new motherboard that has an EFI BIOS (err,  
saying EFI and BIOS is redundant?!) and stick a 3COM 3C905C with PXE,  
and an Intel EEPRO100B, and an RTL8139 with an Etherboot 5.4.cvs ROM,  
and see what happens when I try to load PXELINUX.

Marty





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