Subject: Re: pmap_enter() bashed
To: Charles M. Hannum <email@example.com>
From: Gordon W. Ross <firstname.lastname@example.org>
Date: 03/28/1999 22:17:09
Very interesting! Can you describe when case 1 happens?
(I thought pmap_enter was ONLY called by vm_fault!)
Charles M. Hannum writes:
> Here's a somewhat long-winded explanation, just to make sure I cover
> all the points.
> There are two different reasons why we map pages:
> 1) because we expect to need the page Some Time Later. This can
> happen when, e.g., `prefaulting' pages. In this case the
> `access_type' is set to 0 and no special action is performed by the
> 2) because we need the page Right Now, possibly because we got a
> fault. In this case, we know that the page is going to be accessed
> immediately after the fault handler returns (or, in some cases,
> immediately after pmap_enter() returns, as in /dev/mem handling).