linux-kernel - Re: [PATCH] x86-64: disable the GART in shutdown

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Message-ID: <20070623103947.GA4441@rhun.cust.hotspot.t-mobile.com>
Date:	Sat, 23 Jun 2007 03:39:47 -0700
From:	Muli Ben-Yehuda <muli@...ibm.com>
To:	Yinghai Lu <Yinghai.Lu@....COM>
Cc:	Andi Kleen <ak@...e.de>, Alan Cox <alan@...rguk.ukuu.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vivek Goyal <vgoyal@...ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86-64: disable the GART in shutdown

On Fri, Jun 22, 2007 at 07:34:59PM -0700, Yinghai Lu wrote:
> [PATCH] x86-64: disable the GART in shutdown
> 
> For K8 system: 4G RAM with memory hole remapping enabled, or more than 4G RAM
> installed. when mem is allocated for GART, it will do the memset for clear.
> and for kexec case, the first kernel already enable that, the memset in second
> kernel will cause the system restart. solution will be:
> in second kernel: disable that at first before we try to allocate mem for it.
> or in the first kernel: do disable that before shutdown.
> 
> Signed-off-by: Yinghai Lu <yinghai.lu@....com>
> 

[snip]

> diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
> index 9f80aad..64f2ab3 100644
> --- a/arch/x86_64/kernel/pci-dma.c
> +++ b/arch/x86_64/kernel/pci-dma.c
> @@ -322,6 +322,13 @@ static int __init pci_iommu_init(void)
>  	return 0;
>  }
>  
> +void pci_iommu_shutdown(void)
> +{
> +#ifdef CONFIG_IOMMU
> +	gart_iommu_shutdown();
> +#endif
> +}

I'm going to need exactly the same hook fro Calgary, as well Intel for
VT-d, and AMD for their upcoming IOMMU, etc. How about we do

struct iommu_ops {
  struct dma_ops {
    ...
  }
  void (*shutdown)(void);
}

And then pci_iommu_shutdown() becomes

if (iommu_ops->shutdown)
  iommu_ops->shutdown();

?

Cheers,
Muli

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