From 06e9552f5f12564dc1c3483f0934d96cc4f72f18 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 27 Apr 2018 09:13:24 +0200 Subject: x86/pci-dma: remove the experimental forcesac boot option Limiting the dma mask to avoid PCI (pre-PCIe) DAC cycles while paying the huge overhead of an IOMMU is rather pointless, and this seriously gets in the way of dma mapping work. Signed-off-by: Christoph Hellwig Reviewed-by: Thomas Gleixner --- Documentation/admin-guide/kernel-parameters.txt | 1 - Documentation/x86/x86_64/boot-options.txt | 4 +--- 2 files changed, 1 insertion(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 11fc28ecdb6d..6d4a666748dd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1705,7 +1705,6 @@ nopanic merge nomerge - forcesac soft pt [x86, IA-64] nobypass [PPC/POWERNV] diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 153b3a57fba2..341588ec4e29 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -208,7 +208,7 @@ IOMMU (input/output memory management unit) Kernel boot message: "PCI-DMA: Using Calgary IOMMU" iommu=[][,noagp][,off][,force][,noforce][,leak[=] - [,memaper[=]][,merge][,forcesac][,fullflush][,nomerge] + [,memaper[=]][,merge][,fullflush][,nomerge] [,noaperture][,calgary] General iommu options: @@ -235,8 +235,6 @@ IOMMU (input/output memory management unit) (experimental). nomerge Don't do scatter-gather (SG) merging. noaperture Ask the IOMMU not to touch the aperture for AGP. - forcesac Force single-address cycle (SAC) mode for masks <40bits - (experimental). 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 -- cgit v1.2.3-59-g8ed1b