| Magma: Overview |
| =============== |
| |
| ## Background |
| |
| Fuchsia is a new open source, microkernel-like operating system from Google. Drivers do not execute inside the Zircon kernel, instead they are privileged user-space processes. |
| Drivers are built using a stable [FDF](/docs/development/drivers/concepts/fdf.md). |
| |
| Magma is the gpu driver architecture for Fuchsia. There are two driver components: a gpu-specific library loaded into each application’s address space; and the magma system driver that manages the hardware. |
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| ## Hardware requirements |
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| ### Vulkan conformant gpu |
| Magma is designed to support [Vulkan](/docs/development/graphics/magma/concepts/vulkan.md), though it could be used to implement OpenGL or other graphics APIs. Fuchsia intends to support software consuming OpenGL APIs via translation to Vulkan using ANGLE. |
| |
| ### MMU |
| A memory management unit that allows arbitrary mapping of system memory pages into the GPU address space is needed for DMA to/from non-contiguous buffers. |
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| ### Per-client independent address space |
| For system security it’s important to maintain address space isolation in the gpu domain as well as in the cpu domain. |
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| ### Unified memory architecture |
| This may be relaxed in the future. |
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| ## Architecture |
| |
| Similar to the direct rendering model on Linux, there are two driver components: a gpu-specific library loaded into each application’s address space; and the magma system driver that manages the hardware. |
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| ### Magma system driver |
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| Responsibilities: |
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| * Initializing hardware |
| * Setting up memory spaces |
| * Setting up hardware contexts |
| * Mapping buffers |
| * Scheduling command buffers |
| * Handling faults |
| * Managing power |
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| ### Client library driver |
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| Responsibilities: |
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| * Implementing Vulkan 1.0/1.1/1.2 entry points |
| * Implementing Fuchsia extensions for import and export of external memory and semaphores |
| * Implementing VK_KHR_display and/or VK_KHR_swapchain for direct display access |
| |
| Whereas a traditional client driver makes ioctl syscalls to communicate with a kernel driver; magma provides an interface for client drivers to communicate over IPC with the Magma system driver. |
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| Details on the Magma interface are given in [Magma: Design](/docs/development/graphics/magma/concepts/design.md). |
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