Date: Wed, 5 Nov 2014 20:28:41 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Sourish Mazumder <sourish@cloudbyte.com> Cc: freebsd-amd64@freebsd.org Subject: Re: memory type e820 Message-ID: <20141105182841.GJ53947@kib.kiev.ua> In-Reply-To: <CABv3qbHH81LpBCJHOvHXU817n%2B4_%2B=LWq%2BzGJfAHbpf5qbqpRw@mail.gmail.com> References: <CABv3qbEuggLT=9vsHAs5Rdp8a0V-=DG7DnPO1BQk4Ghn4r_9Dw@mail.gmail.com> <201410301353.05185.jhb@freebsd.org> <CABv3qbHQEFZiQ4p%2BHWZNLt0MiNnHBmDW1aTFhWB7vhr4J3BGfQ@mail.gmail.com> <3381641.WgZAz21Lfu@pippin.baldwin.cx> <20141104084628.GN53947@kib.kiev.ua> <CABv3qbHH81LpBCJHOvHXU817n%2B4_%2B=LWq%2BzGJfAHbpf5qbqpRw@mail.gmail.com>
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On Wed, Nov 05, 2014 at 11:22:21PM +0530, Sourish Mazumder wrote: > Should there be any difference in performance while writing to a memory as > cached versus uncached mapping? Obviously, there should. On the other hand, I do not understand how this question is related to the discussion below. > > On Tue, Nov 4, 2014 at 2:16 PM, Konstantin Belousov <kostikbel@gmail.com> > wrote: > > > 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. > > > > > > -- > Sourish Mazumder > 9986309755
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