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Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules

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On Thu, Jul 6, 2017 at 11:10 PM, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, Jul 06, 2017 at 12:09:45PM +0100, Robin Murphy wrote:
>> I suppose another option is to just make the IOMMU and DMA ops a
>> self-contained non-modular driver mirroring the VT-d/AMD-Vi IOMMUs -
>> AFAICS it shouldn't have to be all that tightly coupled to the IPU bus
>> code, the latter more or less just needs to create the appropriate IOMMU
>> device for the driver to find.
>
> I still haven't seen the driver code, but this seems to be best
> solution so far.  Given that it's not a plug in device but part of
> an SOC that seems perfectly acceptable to me.

I guess that's something that could work. With its caveats of not
being able to avoid including the very platform specific code in a
generic kernel image or do any quick testing of code changes without a
restart, but I guess that's something one could quickly hack in their
own downstream (i.e. export the symbols and turn the Kconfig entry
into tristate).

On the other hand, I'm yet to see any real reasons why not to export
those symbols. Personally I don't see anything that one wouldn't be
able to do in their downstream without the symbols exported in
mainline (one can add the exports any time or if the kernel source
can't be modified can just load a wrapper module that exports its own
symbols...)

Best regards,
Tomasz

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[RFC PATCH 0/5] Fixes for loadable modules implementing DMA/IOMMU APIs Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
  [RFC PATCH 5/5] iommu/dma: Add iommu_dma_cleanup() Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
  [RFC PATCH 2/5] base: dma-mapping: Provide a function to look up remapped pages Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
  [RFC PATCH 3/5] iommu: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
  [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
    Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Christoph Hellwig <hch@lst.de> - 2017-07-05 17:20 +0200
      Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-05 17:30 +0200
        Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Christoph Hellwig <hch@lst.de> - 2017-07-05 19:30 +0200
          Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 03:50 +0200
            Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Arnd Bergmann <arnd@arndb.de> - 2017-07-06 10:30 +0200
              Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 10:40 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 10:50 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Arnd Bergmann <arnd@arndb.de> - 2017-07-06 14:30 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 15:40 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 15:50 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 16:10 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Arnd Bergmann <arnd@arndb.de> - 2017-07-06 16:30 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Tomasz Figa <tfiga@chromium.org> - 2017-07-06 16:40 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Arnd Bergmann <arnd@arndb.de> - 2017-07-06 16:10 +0200
                Re: [RFC PATCH 1/5] base: dma-mapping: Export commonly used symbols Arnd Bergmann <arnd@arndb.de> - 2017-07-06 16:00 +0200
  [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-05 09:20 +0200
    Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in  modules Robin Murphy <robin.murphy@arm.com> - 2017-07-05 18:30 +0200
      Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-06 04:30 +0200
        Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in  modules Robin Murphy <robin.murphy@arm.com> - 2017-07-06 13:20 +0200
          Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use         in modules Christoph Hellwig <hch@lst.de> - 2017-07-06 16:20 +0200
            Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-06 16:20 +0200
              Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-06 16:30 +0200
                Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Arnd Bergmann <arnd@arndb.de> - 2017-07-06 16:40 +0200
                Re: [RFC PATCH 4/5] iommu/dma: Export non-static functions to use in modules Tomasz Figa <tfiga@chromium.org> - 2017-07-06 16:50 +0200

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