220.127.116.11. Descriptor Memory Management
As a part of channel initialization, the driver allocates the memory for descriptors and associates to the channel. Driver uses dma_alloc_coherent API of Linux DMA framework to allocate non-swapable and physically contagious memory.
- By default, currently 1 page is enabled. 1 page contains 128 descriptors. By using ethtool, netdev supports changing the queue size.
- Each queue (H2D & D2H) of each channel gets its descriptor memory.
- After allocation of this memory, the hardware is notified of it by a write of the starting address to the QCSR region.
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