[PATCH 03/16] riscv: qemu: Explain how to extract the generate devicetree

Simon Glass sjg at chromium.org
Wed Oct 13 03:01:07 CEST 2021

QEMU currently generates a devicetree for use with U-Boot. Explain how to
obtain it.

Signed-off-by: Simon Glass <sjg at chromium.org>

 doc/board/emulation/qemu-riscv.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/doc/board/emulation/qemu-riscv.rst b/doc/board/emulation/qemu-riscv.rst
index 4b8e104a215..b3cf7085847 100644
--- a/doc/board/emulation/qemu-riscv.rst
+++ b/doc/board/emulation/qemu-riscv.rst
@@ -113,3 +113,15 @@ An attached disk can be emulated by adding::
     -device ide-hd,drive=mydisk,bus=ahci.0
 You will have to run 'scsi scan' to use it.
+Obtaining the QEMU devicetree
+QEMU generates its own devicetree to pass to U-Boot and does this by default.
+You can use `-dtb u-boot.dtb` to force QEMU to use U-Boot's in-tree version.
+To obtain the devicetree that qemu generates, add `-machine dumpdtb=dtb.dtb`,
+    qemu-system-riscv64 -nographic -machine virt -bios u-boot \
+	    -machine dumpdtb=dtb.dtb

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