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| author | Christoph Hellwig <hch@lst.de> | 2018-04-27 09:13:24 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2018-05-28 12:48:16 +0200 |
| commit | 06e9552f5f12564dc1c3483f0934d96cc4f72f18 (patch) | |
| tree | 48c92eba3b3c1a7e8576fc84159183481e5e2960 /Documentation/x86 | |
| parent | Documentation/x86: remove a stray reference to pci-nommu.c (diff) | |
| download | linux-06e9552f5f12564dc1c3483f0934d96cc4f72f18.tar.xz linux-06e9552f5f12564dc1c3483f0934d96cc4f72f18.zip | |
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 <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/x86_64/boot-options.txt | 4 |
1 files changed, 1 insertions, 3 deletions
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=[<size>][,noagp][,off][,force][,noforce][,leak[=<nr_of_leak_pages>] - [,memaper[=<order>]][,merge][,forcesac][,fullflush][,nomerge] + [,memaper[=<order>]][,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 |