From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Josh Boyer <jwboyer@gmail.com>
Cc: fujita.tomonori@lab.ntt.co.jp, linuxppc-dev@ozlabs.org,
akpm@linux-foundation.org
Subject: Re: [patch 1/1] powerpc: enable ARCH_DMA_ADDR_T_64BIT with ARCH_PHYS_ADDR_T_64BIT
Date: Sat, 02 Oct 2010 13:20:54 +1000 [thread overview]
Message-ID: <1285989654.2463.286.camel@pasglop> (raw)
In-Reply-To: <AANLkTikrgu5LrYfveax_EavObThNw2M4ukVB3ka1y0Hj@mail.gmail.com>
On Fri, 2010-10-01 at 21:31 -0400, Josh Boyer wrote:
> > +config ARCH_DMA_ADDR_T_64BIT
> > + def_bool ARCH_PHYS_ADDR_T_64BIT
> > +
>
> I seemed to have missed what this is about entirely. Is there some
> place I can look that describes what that is supposed to do? The PPC
> 4xx boards set PHYS_ADDR_T_64BIT because the MMU uses 36 bit
> addressing, but the CPU is only 32 bits. I want to make sure this DMA
> thing isn't going to cause problems.
Yes, we need to test a bit. Our dma_addr_t has remained 32-bit so far
because despite the fact that we've had routinely to deal with >32-bit
physical addresses for MMIO, physical memory support has been
constrained afaik to 32-bit.
We might be better off keeping this as something individual platforms
can select...
Cheers,
Ben.
next prev parent reply other threads:[~2010-10-02 3:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-01 21:12 [patch 1/1] powerpc: enable ARCH_DMA_ADDR_T_64BIT with ARCH_PHYS_ADDR_T_64BIT akpm
2010-10-02 1:31 ` Josh Boyer
2010-10-02 3:20 ` Benjamin Herrenschmidt [this message]
2010-10-02 10:11 ` FUJITA Tomonori
2010-10-03 6:20 ` Benjamin Herrenschmidt
2010-10-20 22:56 akpm
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