Date: Tue, 14 Apr 2015 20:36:43 +0200
From: Borislav Petkov <bp@alien8.de>
To: =?utf-8?Q?J=C3=B6rg-Volker?= Peetz <jvpeetz@web.de>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
        bhelgaas@google.com, Suravee.Suthikulpanit@amd.com, joro@8bytes.org
Subject: Re: [PATCH] x86, aperture: Check for GART before accessing GART
 registers
Message-ID: <20150414183643.GF14069@pd.tnic>
References: <20150402100135.GA5210@gmail.com>
 <551D661D.3030000@amd.com>
 <20150402160634.GB8045@gmail.com>
 <551D6CF5.1010604@amd.com>
 <20150402165356.GE4579@pd.tnic>
 <551D7695.2010509@amd.com>
 <20150402171705.GF4579@pd.tnic>
 <552CF6DF.3000002@web.de>
 <20150414113349.GA26075@pd.tnic>
 <552D5AF8.3070705@web.de>
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On Tue, Apr 14, 2015 at 08:22:48PM +0200, Jörg-Volker Peetz wrote:
> thank you for the explanation. Somehow I thought I had a newer CPU w/o
> GART registers, but I misread the patch. Maybe wishful thinking, in
> the hope to save 64 MB :-(

64MB out of how much? Does it even matter?

You could turn off CONFIG_GART_IOMMU and not build aperture_64.c at all.

I think then you'll fall back to swiotlb or whatever and that will most
likely slow down DMA ... the story was something like that, at least,
memory's hazy. Joerg's on CC, he'll correct me if I'm talking bull.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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