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Dumb question.. do USB devices support DMA? Is it done through the host? Or does the USB device always push/pull data to host memory?
by brcmthrowaway 6mo ago
Dumb question.. do USB devices support DMA? Is it done through the host? Or does the USB device always push/pull data to host memory?
- kam 6mo agoUSB devices cannot directly address host memory like PCIe or FireWire, but the XHCI controller does DMA to/from host memory, and most USB device controllers have some kind of DMA between USB and the device's RAM.
- pjc50 6mo agoAll transfers are initiated by the host, including ones that look like they're client-first; there is no DMA, which would be a massive security pain.