diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | Documentation/core-api/dma-api.rst | 14 | ||||
| -rw-r--r-- | Documentation/x86/x86_64/boot-options.rst | 8 |
3 files changed, 23 insertions, 4 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 22d7b5127184..9dc68a12a5bf 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5999,8 +5999,11 @@ it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) swiotlb= [ARM,IA-64,PPC,MIPS,X86] - Format: { <int> | force | noforce } + Format: { <int> [,<int>] | force | noforce } <int> -- Number of I/O TLB slabs + <int> -- Second integer after comma. Number of swiotlb + areas with their own lock. Will be rounded up + to a power of 2. force -- force using of bounce buffers even if they wouldn't be automatically used by the kernel noforce -- Never use bounce buffers (for debugging) diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst index 6d6d0edd2d27..829f20a193ca 100644 --- a/Documentation/core-api/dma-api.rst +++ b/Documentation/core-api/dma-api.rst @@ -206,6 +206,20 @@ others should not be larger than the returned value. :: + size_t + dma_opt_mapping_size(struct device *dev); + +Returns the maximum optimal size of a mapping for the device. + +Mapping larger buffers may take much longer in certain scenarios. In +addition, for high-rate short-lived streaming mappings, the upfront time +spent on the mapping may account for an appreciable part of the total +request lifetime. As such, if splitting larger requests incurs no +significant performance penalty, then device drivers are advised to +limit total DMA streaming mappings length to the returned value. + +:: + bool dma_need_sync(struct device *dev, dma_addr_t dma_addr); diff --git a/Documentation/x86/x86_64/boot-options.rst b/Documentation/x86/x86_64/boot-options.rst index 03ec9cf01181..cbd14124a667 100644 --- a/Documentation/x86/x86_64/boot-options.rst +++ b/Documentation/x86/x86_64/boot-options.rst @@ -287,11 +287,13 @@ iommu options only relevant to the AMD GART hardware IOMMU: iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU implementation: - swiotlb=<pages>[,force] - <pages> - Prereserve that many 128K pages for the software IO bounce buffering. + swiotlb=<slots>[,force,noforce] + <slots> + Prereserve that many 2K slots for the software IO bounce buffering. force Force all IO through the software TLB. + noforce + Do not initialize the software TLB. Miscellaneous |