Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a resource range. (v1.1)

From	Daniel Vetter <daniel@ffwll.ch>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a resource range. (v1.1)
Date	2016-10-26 09:10 +0200
Message-ID	<swqvv-i6-9@gated-at.bofh.it> (permalink)
References	<svH5n-3Tr-1@gated-at.bofh.it> <svH5o-3Tr-15@gated-at.bofh.it> <swdRF-fJ-51@gated-at.bofh.it> <swpg5-7Kg-11@gated-at.bofh.it> <swpJ7-8cX-7@gated-at.bofh.it>
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On Wed, Oct 26, 2016 at 8:12 AM, Dave Airlie <airlied@gmail.com> wrote:
>>> Is anything on a driver to be able to tell when this is actually needed ?
>>> How will driver developers know? Can you add a bit of documentation to
>>> the API? If its transitive towards a secondary solution indicating so
>>> would help driver developers.
>>
>> I'll plug the io-mapping stuff again here, and more specifically the
>> userspace pte wrangling stuff we've added in 4.9 to i915_mm.c. Should
>> probably move that one to the core. That way io_mapping takes care of the
>> full reservartion, and allows you to on-demand kmap (for kernel) and write
>> ptes. All nicely fast and all, and for bonus, also nicely encapsulated.
>
> Yeah I think ideally we'd want to move towards that, however we don't tend
> to want to ioremap the full range even on 64-bit, which is what io-mapping does.

Hm, I thought on 64 we have linear mappings of all the io space
anyway, and they're essentially for free. Am I wrong and there's some
overhead here too?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

Thread

x86 PAT memtype regression fixes (with extra cc's) Dave Airlie <airlied@redhat.com> - 2016-10-24 08:40 +0200
  [PATCH 2/2] drm/drivers: add support for using the arch wc mapping API. Dave Airlie <airlied@redhat.com> - 2016-10-24 08:40 +0200
    Re: [PATCH 2/2] drm/drivers: add support for using the arch wc  mapping API. Christian König <deathsimple@vodafone.de> - 2016-10-24 11:30 +0200
  [PATCH 1/2] x86/io: add interface to reserve io memtype for a resource range. (v1.1) Dave Airlie <airlied@redhat.com> - 2016-10-24 08:40 +0200
    Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) Ingo Molnar <mingo@kernel.org> - 2016-10-25 11:50 +0200
    Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) Thomas Gleixner <tglx@linutronix.de> - 2016-10-25 13:20 +0200
    Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-10-25 19:40 +0200
      Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 07:50 +0200
        Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) Dave Airlie <airlied@gmail.com> - 2016-10-26 08:20 +0200
          Re: [PATCH 1/2] x86/io: add interface to reserve io memtype for a  resource range. (v1.1) Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 09:10 +0200
    [PATCH] x86/pat, mm: Make track_pfn_insert() return void Borislav Petkov <bp@alien8.de> - 2016-10-26 19:50 +0200

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