Subject: Re: Kernel copyin/out optimizations for ARM...
To: None <>
From: David Laight <>
List: port-arm
Date: 03/12/2002 11:54:40
On Tue, Mar 12, 2002 at 10:38:39AM +0000, Richard Earnshaw wrote:
> I've always wondered why that code wasn't written using ldrt/strt for the 
> user-space accesses.  That would then use the hardware for permission 
> checking and eliminate the most expensive part of that code (doing the tlb 
> check manually).

not in ARM v3?
> Maybe there is some reason why that would not work (wrong page tables 
> mapped?)

Isn't there a problem that the cache is checked before the TLBs?
Maybe bound checking the address is enough?

Why did the 'move from/to previous address space' instructions that
the pdp-11 have disappear from most later systems?


David Laight: