path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 14:12:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 14:12:21 -0800
commitaf7ddd8a627c62a835524b3f5b471edbbbcce025 (patch)
treeaf9777ddef6d394c7cc01fca599328b584ca2bc1 /Documentation
parentMerge tag 'for-4.21/libata-20181221' of git://git.kernel.dk/linux-block (diff)
parentdma-mapping: fix inverted logic in dma_supported (diff)
Merge tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping
Pull DMA mapping updates from Christoph Hellwig: "A huge update this time, but a lot of that is just consolidating or removing code: - provide a common DMA_MAPPING_ERROR definition and avoid indirect calls for dma_map_* error checking - use direct calls for the DMA direct mapping case, avoiding huge retpoline overhead for high performance workloads - merge the swiotlb dma_map_ops into dma-direct - provide a generic remapping DMA consistent allocator for architectures that have devices that perform DMA that is not cache coherent. Based on the existing arm64 implementation and also used for csky now. - improve the dma-debug infrastructure, including dynamic allocation of entries (Robin Murphy) - default to providing chaining scatterlist everywhere, with opt-outs for the few architectures (alpha, parisc, most arm32 variants) that can't cope with it - misc sparc32 dma-related cleanups - remove the dma_mark_clean arch hook used by swiotlb on ia64 and replace it with the generic noncoherent infrastructure - fix the return type of dma_set_max_seg_size (Niklas Söderlund) - move the dummy dma ops for not DMA capable devices from arm64 to common code (Robin Murphy) - ensure dma_alloc_coherent returns zeroed memory to avoid kernel data leaks through userspace. We already did this for most common architectures, but this ensures we do it everywhere. dma_zalloc_coherent has been deprecated and can hopefully be removed after -rc1 with a coccinelle script" * tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping: (73 commits) dma-mapping: fix inverted logic in dma_supported dma-mapping: deprecate dma_zalloc_coherent dma-mapping: zero memory returned from dma_alloc_* sparc/iommu: fix ->map_sg return value sparc/io-unit: fix ->map_sg return value arm64: default to the direct mapping in get_arch_dma_ops PCI: Remove unused attr variable in pci_dma_configure ia64: only select ARCH_HAS_DMA_COHERENT_TO_PFN if swiotlb is enabled dma-mapping: bypass indirect calls for dma-direct vmd: use the proper dma_* APIs instead of direct methods calls dma-direct: merge swiotlb_dma_ops into the dma_direct code dma-direct: use dma_direct_map_page to implement dma_direct_map_sg dma-direct: improve addressability error reporting swiotlb: remove dma_mark_clean swiotlb: remove SWIOTLB_MAP_ERROR ACPI / scan: Refactor _CCA enforcement dma-mapping: factor out dummy DMA ops dma-mapping: always build the direct mapping code dma-mapping: move dma_cache_sync out of line dma-mapping: move various slow path functions out of line ...
Diffstat (limited to 'Documentation')
3 files changed, 15 insertions, 52 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index ac66ae2509a9..e133ccd60228 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -60,15 +60,6 @@ the returned memory, like GFP_DMA).
- void *
- dma_zalloc_coherent(struct device *dev, size_t size,
- dma_addr_t *dma_handle, gfp_t flag)
-Wraps dma_alloc_coherent() and also zeroes the returned memory if the
-allocation attempt succeeded.
dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle)
@@ -717,12 +708,15 @@ dma-api/num_errors The number in this file shows how many
dma-api/min_free_entries This read-only file can be read to get the
minimum number of free dma_debug_entries the
allocator has ever seen. If this value goes
- down to zero the code will disable itself
- because it is not longer reliable.
+ down to zero the code will attempt to increase
+ nr_total_entries to compensate.
dma-api/num_free_entries The current number of free dma_debug_entries
in the allocator.
+dma-api/nr_total_entries The total number of dma_debug_entries in the
+ allocator, both free and used.
dma-api/driver-filter You can write a name of a driver into this file
to limit the debug output to requests from that
particular driver. Write an empty string to
@@ -742,10 +736,15 @@ driver filter at boot time. The debug code will only print errors for that
driver afterwards. This filter can be disabled or changed later using debugfs.
When the code disables itself at runtime this is most likely because it ran
-out of dma_debug_entries. These entries are preallocated at boot. The number
-of preallocated entries is defined per architecture. If it is too low for you
-boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
-architectural default.
+out of dma_debug_entries and was unable to allocate more on-demand. 65536
+entries are preallocated at boot - if this is too low for you boot with
+'dma_debug_entries=<your_desired_number>' to overwrite the default. Note
+that the code allocates entries in batches, so the exact number of
+preallocated entries may be greater than the actual number requested. The
+code will print to the kernel log each time it has dynamically allocated
+as many entries as were initially preallocated. This is to indicate that a
+larger preallocation size may be appropriate, or if it happens continually
+that a driver may be leaking mappings.
diff --git a/Documentation/features/io/sg-chain/arch-support.txt b/Documentation/features/io/sg-chain/arch-support.txt
deleted file mode 100644
index 6554f0372c3f..000000000000
--- a/Documentation/features/io/sg-chain/arch-support.txt
+++ /dev/null
@@ -1,33 +0,0 @@
-# Feature name: sg-chain
-# description: arch supports chained scatter-gather lists
- -----------------------
- | arch |status|
- -----------------------
- | alpha: | TODO |
- | arc: | ok |
- | arm: | ok |
- | arm64: | ok |
- | c6x: | TODO |
- | h8300: | TODO |
- | hexagon: | TODO |
- | ia64: | ok |
- | m68k: | TODO |
- | microblaze: | TODO |
- | mips: | TODO |
- | nds32: | TODO |
- | nios2: | TODO |
- | openrisc: | TODO |
- | parisc: | TODO |
- | powerpc: | ok |
- | riscv: | TODO |
- | s390: | ok |
- | sh: | TODO |
- | sparc: | ok |
- | um: | TODO |
- | unicore32: | TODO |
- | x86: | ok |
- | xtensa: | TODO |
- -----------------------
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index ad6d2a80cf05..abc53886655e 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -209,7 +209,7 @@ IOMMU (input/output memory management unit)
mapping with memory protection, etc.
Kernel boot message: "PCI-DMA: Using Calgary IOMMU"
- iommu=[<size>][,noagp][,off][,force][,noforce][,leak[=<nr_of_leak_pages>]
+ iommu=[<size>][,noagp][,off][,force][,noforce]
@@ -228,9 +228,6 @@ IOMMU (input/output memory management unit)
allowed Overwrite iommu off workarounds for specific chipsets.
fullflush Flush IOMMU on each allocation (default).
nofullflush Don't use IOMMU fullflush.
- leak Turn on simple iommu leak tracing (only when
- CONFIG_IOMMU_LEAK is on). Default number of leak pages
- is 20.
memaper[=<order>] Allocate an own aperture over RAM with size 32MB<<order.
(default: order=1, i.e. 64MB)
merge Do scatter-gather (SG) merging. Implies "force"