doc: debug UART for RISC-V QEMU virt machine

Provide settings for enabling the debug UART of the virt machine on
RISC-V QEMU.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

diff --git a/doc/board/emulation/qemu-riscv.rst b/doc/board/emulation/qemu-riscv.rst
index ae998810c8776be81fc59229940ccd4329cb3ac9..782f37251c39eef57cfee2923fd5f7a2b00ec57d 100644 (file)
--- a/doc/board/emulation/qemu-riscv.rst
+++ b/doc/board/emulation/qemu-riscv.rst
@@ -132,3 +132,13 @@ An attached disk can be emulated in RISC-V virt machine by adding::
     -device ide-hd,drive=mydisk,bus=ahci.0
 
 You will have to run 'scsi scan' to use it.
+
+Debug UART
+----------
+
+The following settings provide a debug UART for the virt machine::
+
+    CONFIG_DEBUG_UART=y
+    CONFIG_DEBUG_UART_NS16550=y
+    CONFIG_DEBUG_UART_BASE=0x10000000
+    CONFIG_DEBUG_UART_CLOCK=3686400