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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
To: akataria@vmware.com
Cc: konrad.wilk@oracle.com, ak@linux.intel.com, lenb@kernel.org,
	x86@kernel.org, linux-acpi@vger.kernel.org,
	linux-kernel@vger.kernel.org, petr@vmware.com
Subject: Re: swiotlb detection should be memory hotplug aware ?
Date: Thu, 22 Jul 2010 09:03:57 +0900	[thread overview]
Message-ID: <20100722090329O.fujita.tomonori@lab.ntt.co.jp> (raw)
In-Reply-To: <20100722084413I.fujita.tomonori@lab.ntt.co.jp>

On Thu, 22 Jul 2010 08:44:42 +0900
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:

> On Wed, 21 Jul 2010 10:13:34 -0700
> Alok Kataria <akataria@vmware.com> wrote:
> 
> > > Basically, you want to add hot-plug memory and enable swiotlb, right?
> > 
> > Not really, I am planning to do something like this, 
> > 
> > @@ -52,7 +52,7 @@ int __init pci_swiotlb_detect(void)
> >  
> >  	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
> >  #ifdef CONFIG_X86_64
> > -	if (!no_iommu && max_pfn > MAX_DMA32_PFN)
> > +	if (!no_iommu && (max_pfn > MAX_DMA32_PFN || hotplug_possible()))
> >  		swiotlb = 1;
> 
> Always enable swiotlb with memory hotplug enabled? Wasting 64MB on a
> x86_64 system with 128MB doesn't look to be a good idea. I don't think
> that there is an easy solution for this issue though.

btw, you need more work to enable switch on the fly.

You need to change the dma_ops pointer (see get_dma_ops()). It means
that you need to track outstanding dma operations per device, locking,
etc.

  reply	other threads:[~2010-07-22  0:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-13  2:07 swiotlb detection should be memory hotplug aware ? Alok Kataria
2010-03-13  3:09 ` Andi Kleen
2010-03-15 17:22   ` Alok Kataria
2010-03-16  0:51   ` [LKML] " Konrad Rzeszutek Wilk
2010-03-16  1:33     ` FUJITA Tomonori
2010-03-16 12:45       ` [LKML] " Konrad Rzeszutek Wilk
2010-03-17 22:48         ` Alok Kataria
2010-07-20 22:14           ` Alok Kataria
2010-07-21  4:58             ` FUJITA Tomonori
2010-07-21 17:13               ` Alok Kataria
2010-07-21 23:44                 ` FUJITA Tomonori
2010-07-22  0:03                   ` FUJITA Tomonori [this message]
2010-07-22 18:34                     ` Alok Kataria
2010-07-23 14:22                       ` Konrad Rzeszutek Wilk
2010-07-23 14:33                         ` Andi Kleen
2010-07-23 14:59                           ` Konrad Rzeszutek Wilk
2010-07-23 15:23                             ` Andi Kleen
2010-07-28 10:10                               ` FUJITA Tomonori
2010-07-28 11:09                                 ` Andi Kleen
2010-07-28 14:20                                   ` FUJITA Tomonori

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