From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936325AbeEYOfp (ORCPT ); Fri, 25 May 2018 10:35:45 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:56750 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936299AbeEYOfl (ORCPT ); Fri, 25 May 2018 10:35:41 -0400 From: Christoph Hellwig To: Thomas Gleixner , Ingo Molnar , Tony Luck , Fenghua Yu , Greg Kroah-Hartman Cc: x86@kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH 6/7] x86: remove the explicit nodac and allowdac option Date: Fri, 25 May 2018 16:35:11 +0200 Message-Id: <20180525143512.1466-7-hch@lst.de> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180525143512.1466-1-hch@lst.de> References: <20180525143512.1466-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is something drivers should decide (modulo chipset quirks like for VIA), which as far as I can tell is how things have been handled for the last 15 years. Note that we keep the usedac option for now, as it is used in the wild to override the too generic VIA quirk. Signed-off-by: Christoph Hellwig --- Documentation/x86/x86_64/boot-options.txt | 5 ----- arch/x86/kernel/pci-dma.c | 4 ++-- 2 files changed, 2 insertions(+), 7 deletions(-) diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 341588ec4e29..8d109ef67ab6 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -236,11 +236,6 @@ IOMMU (input/output memory management unit) nomerge Don't do scatter-gather (SG) merging. noaperture Ask the IOMMU not to touch the aperture for AGP. noagp Don't initialize the AGP driver and use full aperture. - allowdac Allow double-address cycle (DAC) mode, i.e. DMA >4GB. - DAC is used with 32-bit PCI to push a 64-bit address in - two cycles. When off all DMA over >4GB is forced through - an IOMMU or software bounce buffering. - nodac Forbid DAC mode, i.e. DMA >4GB. panic Always panic when IOMMU overflows. calgary Use the Calgary IOMMU if it is available diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 91dff954b745..b5cbef974bd1 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -125,9 +125,9 @@ static __init int iommu_setup(char *p) if (!strncmp(p, "forcesac", 8)) pr_warn("forcesac option ignored.\n"); if (!strncmp(p, "allowdac", 8)) - forbid_dac = 0; + pr_warn("allowdac option ignored.\n"); if (!strncmp(p, "nodac", 5)) - forbid_dac = 1; + pr_warn("nodac option ignored.\n"); if (!strncmp(p, "usedac", 6)) { forbid_dac = -1; return 1; -- 2.17.0