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* QEMU Firmware Configuration bindings for ARM
QEMU's arm-softmmu and aarch64-softmmu emulation / virtualization targets
provide the following Firmware Configuration interface on the "virt" machine
type:
- A write-only, 16-bit wide selector (or control) register,
- a read-write, 64-bit wide data register.
QEMU exposes the control and data register to ARM guests as memory mapped
registers; their location is communicated to the guest's UEFI firmware in the
DTB that QEMU places at the bottom of the guest's DRAM.
The authoritative guest-side hardware interface documentation to the fw_cfg
device can be found in "docs/specs/fw_cfg.txt" in the QEMU source tree.
Required properties:
- compatible: "qemu,fw-cfg-mmio".
- reg: the MMIO region used by the device.
* Bytes 0x0 to 0x7 cover the data register.
* Bytes 0x8 to 0x9 cover the selector register.
* Further registers may be appended to the region in case of future interface
revisions / feature bits.
Example:
/ {
#size-cells = <0x2>;
#address-cells = <0x2>;
fw-cfg@9020000 {
compatible = "qemu,fw-cfg-mmio";
reg = <0x0 0x9020000 0x0 0xa>;
};
};
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