Use a patched version of opensbi fu540.elf

tools/opensbi/README.md

@@ -2,14 +2,12 @@
 
 These are binary release of OpenSBI on this [commit](https://github.com/riscv/opensbi/tree/194dbbe5a13dff2255411c26d249f3ad4ef42c0b) at 2019.04.15.
 
-- fu540.elf: opensbi-0.3-rv64-bin/platform/sifive/fu540/firmware/fw_jump.elf
 - virt_rv32.elf: opensbi-0.3-rv32-bin/platform/qemu/virt/firmware/fw_jump.elf
 - virt_rv64.elf: opensbi-0.3-rv64-bin/platform/qemu/virt/firmware/fw_jump.elf
 
-NOTE: The [official v0.3 release](https://github.com/riscv/opensbi/releases/tag/v0.3) has bug on serial interrupt.
+NOTE: The [official v0.3 release](https://github.com/riscv/opensbi/releases/tag/v0.3) has bug on serial interrupt. Also, Rocket-Chip based CPUs (including SiFive Unleashed) seem to have unintended behavior on
 
+For K210 & SiFive Unleashed: It needs some modification. The binary is from this [commit](https://github.com/rcore-os/opensbi/commit/a9638d092756975ceb50073d736a17cef439c7b6).
 
-
-For K210: It needs some modification. The binary is from this [commit](https://github.com/rcore-os/opensbi/commit/4400a1a7d40b5399b3e07b4bad9fd303885c8c16).
-
-* k210.elf: build/platform/kendryte/k210/firmware/fw_payload.elf
+* k210.elf: build/platform/kendryte/k210/firmware/fw_payload.elf
+* fu540.elf: build/platform/sifive/fu540/firmware/fw_jump.elf