svn commit: r268624 - head/sys/dev/vt/hw/efifb

[Konstantin Belousov]

On Mon, Jul 14, 2014 at 11:43:03AM -0700, Nathan Whitehorn wrote:
> 
> On 07/14/14 10:53, Konstantin Belousov wrote:
> > On Mon, Jul 14, 2014 at 05:42:22PM +0000, Nathan Whitehorn wrote:
> >> +	info->fb_vbase = (intptr_t)pmap_mapdev_attr(info->fb_pbase,
> >> +	    info->fb_size, VM_MEMATTR_WRITE_COMBINING);
> >> +}
> >> +
> > Could you use pmap_change_attr() ? This would save some KVA.
> 
> Does that work with the direct map? I'm pretty hesitant to muck with the 
> direct map region this way...

Yes, it works on direct map.

Note that Intel explicitely states that the behaviour is undefined
if the same physical page is mapped with differrent caching attributes.
At least some revisions of Pentium IV hang in this situation.

We keep direct map mapping attributes consistent with other mappings.
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