linux-kernel - Re: [PATCH] x86: fix iommu=nodac parameter handling

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Message-ID: <20091104122827.GB11968@elte.hu>
Date:	Wed, 4 Nov 2009 13:28:27 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Tejun Heo <tj@...nel.org>, Joerg Roedel <joerg.roedel@....com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	David Woodhouse <dwmw2@...radead.org>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Cc:	the arch/x86 maintainers <x86@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, athena@...w.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: fix iommu=nodac parameter handling


* Tejun Heo <tj@...nel.org> wrote:

> nodac should forbid dac instead of enabling it.  Fix it.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Matteo Frigo <athena@...w.org>
> Cc: stable@...nel.org
> ---
> This was posted several months ago in a two patch series.  The second
> one was rejected by Alan and with that the first one got lost too
> although it's an apparent bug fix.  Matteo hit this bug recently and
> reminded me about this patch.  So, regenerated and reposting.
> 
> Thanks.
> 
>  arch/x86/kernel/pci-dma.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index d20009b..8cf3996 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -216,7 +216,7 @@ static __init int iommu_setup(char *p)
>  		if (!strncmp(p, "allowdac", 8))
>  			forbid_dac = 0;
>  		if (!strncmp(p, "nodac", 5))
> -			forbid_dac = -1;
> +			forbid_dac = 1;
>  		if (!strncmp(p, "usedac", 6)) {
>  			forbid_dac = -1;
>  			return 1;

(Cc:-ed more interested parties.)

	Ingo
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