Re: [PATCH] dma: use %pa to print dma_addr_t

From: Olof Johansson
Date: Thu Sep 12 2013 - 13:45:19 EST


On Thu, Sep 12, 2013 at 10:35 AM, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> On Thu, Sep 12, 2013 at 10:11:44AM -0700, Olof Johansson wrote:
>> Any >32bit-addressable machine will likely want 64-bit dma_addr_t as
>> well. The only architecture that doesn't seem to set
>> ARCH_DMA_ADDR_T_64BIT based on PHYS_ADDR_T size is ARM, and I think
>> that should just be changed there as well.

The thread Joe linked to refers to a comment that is now deleted;
sparc64 apparantly has 32-bit dma_addr_t at least, so there are
platforms where the two differ permanently. Adding a new printk format
is probably needed here after all.

> Do we actually have any 64-bit DMA controllers out there? As far as
> I'm aware, all our DMA controllers are all 32-bit address only. That
> makes a 64-bit dma_addr_t rather silly.

PCI/PCI-e is the large unknown here, I'm not actually sure if any of
the current implementation of host controllers support it, but it
would seem likely that server-class hardware does.


-Olof
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