Date: Wed, 5 Nov 2014 23:22:21 +0530 From: Sourish Mazumder <sourish@cloudbyte.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-amd64@freebsd.org Subject: Re: memory type e820 Message-ID: <CABv3qbHH81LpBCJHOvHXU817n%2B4_%2B=LWq%2BzGJfAHbpf5qbqpRw@mail.gmail.com> In-Reply-To: <20141104084628.GN53947@kib.kiev.ua> 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>
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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@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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