Re: Calculating kernel logical address ..

From: David S. Miller (davem@redhat.com)
Date: Mon Sep 09 2002 - 00:00:08 EST


   From: Daniel Phillips <phillips@arcor.de>
   Date: Sun, 8 Sep 2002 20:44:17 +0200

> For anything else you're in non-portablt land, including and
> in partiular:
>
> 1) kernel stack addresses
   
   Could you elaborate on what bad things happen here?
   
Kernel stack allocation is defined per-architecture. On
sun4c sparc systems, we carve virtual pages out from the kernel
address space and hard map them into the TLB by hand.

> 2) addresses within the main kernel image text/data/bss
   
   Yep. MIPS's KSEG0 (a stupid design if there ever was one)

Actually, KSEG0 the most Linux friendly design in the world
particularly in 64-bit mode. There is no need to have page tables at
all for the main kernel physical memory map. It would shave a lot of
code from the sparc64 TLB miss handlers if I didn't have to handle
PAGE_OFFSET pages, for example.

Alpha does something akin to KSEG0 as well.

I pine constantly for it appearing some day on a future UltraSPARC
revision :-)
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