From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Timur Tabi <timur@freescale.com>
Cc: Wood Scott-B07421 <B07421@freescale.com>,
Hu Mingkai-B21284 <B21284@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Xie Shaohui-B21989 <B21989@freescale.com>,
Chen Yuanquan-B41889 <B41889@freescale.com>
Subject: Re: [PATCH] powerpc/mm: add ZONE_NORMAL zone for 64 bit kernel
Date: Tue, 24 Jul 2012 09:29:46 +1000 [thread overview]
Message-ID: <1343086186.2957.46.camel@pasglop> (raw)
In-Reply-To: <500DDB1B.9030900@freescale.com>
On Mon, 2012-07-23 at 18:15 -0500, Timur Tabi wrote:
> Benjamin Herrenschmidt wrote:
> > Sure, that's the right way to go, I meant bits of pieces of the
> > infrastructure in between. Why diverge from other archs gratuituously
> > here ?
>
> Ok, I'm confused. Are you suggesting that drivers do this:
>
> u64 fsl_dma_dmamask = DMA_BIT_MASK(36);
> dev->dma_mask = &fsl_dma_dmamask;
> v = dma_alloc_coherent(dev, ..., GFP_DMA32);
>
> That is, set the DMA mask *and* set GFP_DMA32? That seems redundant.
No, but dma_alloc_coherent would under the hood.
> I don't understand why a driver would set GFP_DMA32 if it has already set
> the mask.
The layers in between, not the well behaved drivers. Again, we have
ZONE_DMA32 specifically for the purpose, why use something else ?
In any case, make the whole thing at the very least a config option, I
don't want sane HW to have to deal with split zones.
Cheers,
Ben.
next prev parent reply other threads:[~2012-07-23 23:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 12:21 [PATCH] powerpc/mm: add ZONE_NORMAL zone for 64 bit kernel Shaohui Xie
2012-07-23 6:06 ` Benjamin Herrenschmidt
2012-07-23 16:17 ` Scott Wood
2012-07-23 22:20 ` Benjamin Herrenschmidt
2012-07-23 23:08 ` Tabi Timur-B04825
2012-07-23 23:12 ` Benjamin Herrenschmidt
2012-07-23 23:15 ` Timur Tabi
2012-07-23 23:29 ` Benjamin Herrenschmidt [this message]
2012-07-23 23:30 ` Benjamin Herrenschmidt
2012-07-24 1:37 ` Scott Wood
2012-07-23 23:36 ` Timur Tabi
2012-07-24 3:08 ` Benjamin Herrenschmidt
2012-07-24 3:52 ` Tabi Timur-B04825
2012-07-24 3:59 ` Zang Roy-R61911
2012-07-24 4:04 ` Tabi Timur-B04825
2012-07-24 4:45 ` Benjamin Herrenschmidt
2012-07-24 8:01 ` Bhushan Bharat-R65777
2012-07-24 1:49 ` Scott Wood
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