Re: Patch to reorder functions in the vmlinux to a defined order

[Andi Kleen <ak@suse.de>]

On Thursday 23 February 2006 18:08, Linus Torvalds wrote:
> 
> On Thu, 23 Feb 2006, Arjan van de Ven wrote:
> > > 
> > > I think you would first need to move the code first for that. Currently it starts
> > > at 1MB, which means 1MB is already wasted of the aligned 2MB TLB entry.
> > > 
> > > I wouldn't have a problem with moving the 64bit kernel to 2MB though.
> > 
> > that was easy since it's a Config entry already ;)
> 
> Btw, the "low TLB entry" for the direct-mapped case can't be used as a 
> hugetlb page anyway, due to the MMU splitting it up due to the special 
> MTRR regions, if I recall correctly.

I was to suggest the same thing originally, but on several boxes I checked
there weren't any special MTRRs < 1MB, only in the PCI memory hole
<4GB. I suspect there isn't just any interesting hardware in 640K anymore.

BTW I have been also pondering some time to really trust e820 and not
forcibly reserve 640K-1MB on 64bit.  That code was inherited from i386,
but probably never made too much sense

[I remember actually taking it out very early, but then putting
it back when I was hunting some insidious unrelated bug. But it wasn't that]

Perhaps that would be a good idea to ignore that newer i386 systems too 
(newer defined as having DMI BIOS dates >2000 or so) 

-Andi