[PATCH 1/3] x86/pat: export io memory reserve/free api.

Edward O'Callaghan funfunctor at folklore1984.net
Tue Oct 18 12:31:23 UTC 2016



On 10/18/2016 07:29 PM, Dave Airlie wrote:
> On 18 Oct. 2016 17:23, "Edward O'Callaghan" <funfunctor at folklore1984.net
> <mailto:funfunctor at folklore1984.net>> wrote:
>>
>> NACK,
>>
>> I think you want to use 'iomap_create_wc()' instead to avoid aliasing.
> 
> Please explain what can alias here?

Ah disregard the alias comment, I was remembering how it was introduced
and that referred to 'io_mapping_create_wc()' not hard coding WC.

Any way, I think 'iomap_create_wc()' is what your looking for so no need
to expose those symbols and hook them though.

Cheers,
Edward.

> 
> Dave.
> 
>>
>> Kind Regards,
>> Edward.
>>
>> On 10/18/2016 05:13 PM, Dave Airlie wrote:
>> > From: Dave Airlie <airlied at redhat.com <mailto:airlied at redhat.com>>
>> >
>> > These functions are needed for gpu/ttm drivers to reserve the
>> > VRAM area as write combined. In a lot of places we don't ioremap
>> > but still need to insert pfn from it into a VMA using vm_insert_mixed,
>> > but a recent change in mixed insertion means we need to reserve
>> > VRAM as WC upfront, so we need these APIs exported.
>> >
>> > Signed-off-by: Dave Airlie <airlied at redhat.com
> <mailto:airlied at redhat.com>>
>> > ---
>> >  arch/x86/mm/pat.c | 2 ++
>> >  1 file changed, 2 insertions(+)
>> >
>> > diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
>> > index 170cc4f..5ce2fbb 100644
>> > --- a/arch/x86/mm/pat.c
>> > +++ b/arch/x86/mm/pat.c
>> > @@ -719,6 +719,7 @@ out_free:
>> >  out_err:
>> >       return ret;
>> >  }
>> > +EXPORT_SYMBOL(io_reserve_memtype);
>> >
>> >  /**
>> >   * io_free_memtype - Release a memory type mapping for a region of
> memory
>> > @@ -729,6 +730,7 @@ void io_free_memtype(resource_size_t start,
> resource_size_t end)
>> >  {
>> >       free_memtype(start, end);
>> >  }
>> > +EXPORT_SYMBOL(io_free_memtype);
>> >
>> >  pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
>> >                               unsigned long size, pgprot_t vma_prot)
>> >
>>
> 

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