From 41c6b3e8989e79772a50429d92cf91959bcce96d Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 16 Dec 2016 14:28:42 +0100 Subject: swiotlb: Add swiotlb=noforce debug option commit fff5d99225107f5f13fe4a9805adc2a1c4b5fb00 upstream. On architectures like arm64, swiotlb is tied intimately to the core architecture DMA support. In addition, ZONE_DMA cannot be disabled. To aid debugging and catch devices not supporting DMA to memory outside the 32-bit address space, add a kernel command line option "swiotlb=noforce", which disables the use of bounce buffers. If specified, trying to map memory that cannot be used with DMA will fail, and a rate-limited warning will be printed. Note that io_tlb_nslabs is set to 1, which is the minimal supported value. Signed-off-by: Geert Uytterhoeven Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- include/linux/swiotlb.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 746ecebbd4ca..d2613536fd03 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -12,6 +12,7 @@ struct scatterlist; enum swiotlb_force { SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */ SWIOTLB_FORCE, /* swiotlb=force */ + SWIOTLB_NO_FORCE, /* swiotlb=noforce */ }; extern enum swiotlb_force swiotlb_force; -- cgit v1.2.3