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Diffstat (limited to 'third_party/rust/ashmem/README.md')
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diff --git a/third_party/rust/ashmem/README.md b/third_party/rust/ashmem/README.md new file mode 100644 index 0000000000..ce19cf4e15 --- /dev/null +++ b/third_party/rust/ashmem/README.md @@ -0,0 +1,14 @@ +# ashmem-rs + +Provides a compatibility interface for Android 8.0's public ASharedMemory API. + +Some variant of ashmem has existed in Android as a private API for some time. Originally available only via [direct ioctl interface](https://elixir.bootlin.com/linux/v5.11.8/source/drivers/staging/android/uapi/ashmem.h), it later became callable (still private) via ashmem_create_region (et al.) in libcutils. + +[ASharedMemory](https://developer.android.com/ndk/reference/group/memory) is the public API to ashmem made available in Android 8.0 (API level 26). +Builds targeting Android 10 (API 29) are no longer permitted to access ashmem via the ioctl interface. This makes life for a portable program difficult - you can't reliably use the old or new interface during this transition period. + +ashmem-rs provides a simple wrapper around the ASharedMemory API, directly calling the public API implementation via dynamically loaded libandroid where available, and falling back to the direct ioctl interface elsewhere. + +References: + - [ASharedMemory documentation](https://developer.android.com/ndk/reference/group/memory) + - [Linux kernel ashmem.h definitions](https://elixir.bootlin.com/linux/v5.11.8/source/drivers/staging/android/uapi/ashmem.h) |