Subject: Re: controlling mmap() cache attributes on i386?
To: Jonathan Stone <email@example.com>
From: Jason Thorpe <firstname.lastname@example.org>
Date: 09/19/1996 09:04:25
On Thu, 19 Sep 1996 01:47:37 -0700
Jonathan Stone <jonathan@DSG.Stanford.EDU> wrote:
> The x86 TLB entries seem to support this, other port's pmap
> interface support setting bits to enable or disable caching
> (e.g., sparc); yet I can't seem to find how to do this on i386.
> Am I missing something obvious?
In machdep.c, look at bus_mem_map() ... look for the calls to
pmap_changebit(). You basically want to set PG_N in the pte.
I'm not sure, exactly, how you'll massage this into the d_mmap routine,
but that's how you make the mapping uncacheable, anyhow...
-- save the ancient forests - http://www.bayarea.net/~thorpej/forest/ --
Jason R. Thorpe email@example.com
NASA Ames Research Center Home: 408.866.1912
NAS: M/S 258-6 Work: 415.604.0935
Moffett Field, CA 94035 Pager: 415.428.6939