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Contact

2017-10-10

IP Status

No known IP claims.

Contributors
• Lina Versace, Google

• James Jones, NVIDIA

• Faith Ekstrand, Intel

Description

A dma_buf is a type of file descriptor, defined by the Linux kernel, that allows sharing memory across kernel device drivers and across processes. This extension enables applications to import a dma_buf as VkDeviceMemory, to export VkDeviceMemory as a dma_buf, and to create VkBuffer objects that can be bound to that memory.

New Enum Constants

• VK_EXT_EXTERNAL_MEMORY_DMA_BUF_EXTENSION_NAME

• VK_EXT_EXTERNAL_MEMORY_DMA_BUF_SPEC_VERSION

• Extending VkExternalMemoryHandleTypeFlagBits:

• VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT

Issues

1) How does the application, when creating a VkImage that it intends to bind to dma_buf VkDeviceMemory containing an externally produced image, specify the memory layout (such as row pitch and DRM format modifier) of the VkImage? In other words, how does the application achieve behavior comparable to that provided by EGL_EXT_image_dma_buf_import and EGL_EXT_image_dma_buf_import_modifiers ?

RESOLVED: Features comparable to those in EGL_EXT_image_dma_buf_import and EGL_EXT_image_dma_buf_import_modifiers will be provided by an extension layered atop this one.

2) Without the ability to specify the memory layout of external dma_buf images, how is this extension useful?

RESOLVED: This extension provides exactly one new feature: the ability to import/export between dma_buf and VkDeviceMemory. This feature, together with features provided by VK_KHR_external_memory_fd, is sufficient to bind a VkBuffer to dma_buf.

Version History

• Revision 1, 2017-10-10 (Lina Versace)

• Squashed internal revisions