memory type e820

Konstantin Belousov kostikbel at
Tue Nov 4 08:46:38 UTC 2014

On Mon, Nov 03, 2014 at 01:52:44PM -0500, John Baldwin wrote:
> On Saturday 01 November 2014 18:55:53 Sourish Mazumder wrote:
> > Hi John,
> > 
> > I tried the pmap_mapdev() as suggested by you. Works perfectly. Thanks for
> > the information.
> Sure.
> > What is required, If I want to add this nvram memory to VM pages?
> Hmm.  If this is device memory you generally don't want that.  I'm not 
> actually sure how to do this at runtime.  If you don't mind having a local
> hack you can add a change in the MD startup code (e.g. in hammer_time()
> in sys/amd64/amd64/machdep.c) to adjust the ranges added to
> phys_avail[] and dump_avail[].

The facility exists to do this.  It is OBJT_MGTDEVICE pager and
vm_phys_fictitious_reg_range().  This is used by i915 and TTM for
aperture, and seems XEN dom0 code uses it for mapping pages from
other domains into dom0.

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