Update polarfire.md

Added some (hopefully) helpful additional content about booting on QEMY emulated polarfire.

Signed-off-by: sand7000 <[email protected]>

Hardware/polarfire.md

@@ -117,3 +117,19 @@ fatload mmc 0 0x1000200000 seL4-uImage
 fatload mmc 0 0x1020200000 kernel.dtb
 bootm 0x1000200000 - 0x1020200000
 ```
+
+## Booting on emulated Polarfire in QEMU
+
+QEMU support emulation of the polarfire and can boot sel4test via direct kernel boot like this:
+
+```
+qemu-system-riscv64 -M microchip-icicle-kit -smp 5 -m 2G -display none -serial stdio -serial null -serial null -kernel images/sel4test-driver-image-riscv-polarfire -dtb mpfs_icicle.dtb
+```
+
+where the dtb is generated by running:
+
+```
+dtc -I dts -O dtb seL4/tools/dts/mpfs_icicle.dts > mpfs_icicle.dtb
+```
+
+note that the dtb has ommitted any overlays that were used by seL4 because they caused QEMU to not print to the UART.