memory type e820
sourish at cloudbyte.com
Wed Nov 5 17:52:30 UTC 2014
Should there be any difference in performance while writing to a memory as
cached versus uncached mapping?
On Tue, Nov 4, 2014 at 2:16 PM, Konstantin Belousov <kostikbel at gmail.com>
> 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
> > > 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
> > 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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