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The GVE family supports two incompatible descriptor queue formats: * GQI: in-order descriptor queues * DQO: out-of-order descriptor queues and two addressing modes: * QPL: pre-registered queue page list addressing * RDA: raw DMA addressing All four combinations (GQI-QPL, GQI-RDA, DQO-QPL, and DQO-RDA) are theoretically supported by the Linux driver, which is essentially the only public reference provided by Google. The original versions of the GVE NIC supported only GQI-QPL mode, and so the iPXE driver is written to target this mode, on the assumption that it would continue to be supported by all models of the GVE NIC. This assumption turns out to be incorrect: Google does not deem it necessary to retain backwards compatibility. Some newer machine types (such as a4-highgpu-8g) support only the DQO-RDA operating mode. Add a definition of operating mode, and pass this as an explicit parameter to the "configure device resources" admin queue command. We choose a representation that subtracts one from the value passed in this command, since this happens to allow us to decompose the mode into two independent bits (one representing the use of DQO descriptor format, one representing the use of QPL addressing). Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE README File Quick start guide: cd src make For any more detailed instructions, see http://ipxe.org