From eb79d8fcf0632582dfcc0dea01cdf6f89a664926 Mon Sep 17 00:00:00 2001
From: Miquel Sabaté Solà <mssola@mssola.com>
Date: Fri, 3 Oct 2025 16:20:14 +0200
Subject: run-riscv-qemu.sh: Add '-k/--kernel' and '-d/--disk' parameters
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This allows this script to be more specific on the kernel being used,
less hiden (as it was on an environment variable), and it easies up the
route for a disk already containing a Linux system.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
---
 bin/run-riscv-qemu.sh | 130 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 83 insertions(+), 47 deletions(-)

diff --git a/bin/run-riscv-qemu.sh b/bin/run-riscv-qemu.sh
index 5098beb..77bf808 100755
--- a/bin/run-riscv-qemu.sh
+++ b/bin/run-riscv-qemu.sh
@@ -1,40 +1,21 @@
 #!/usr/bin/env bash
 
-set -e
+set -ex
 
-# Enfore BUSYBOX_SRC and QEMU_KERNEL.
-if [ -z "$BUSYBOX_SRC" ]; then
-    echo "run-riscv-qemu (error): you need to define BUSYBOX_SRC."
-    exit 1
-fi
-
-# If the $QEMU_KERNEL environment variable is not explicitely set, then guess
-# one based on the current working directory.
-if [ -z "$QEMU_KERNEL" ]; then
-    if [ ! -z "$ARCH" ]; then
-        if [ -f "arch/$ARCH/boot/Image" ]; then
-            QEMU_KERNEL=$(realpath "arch/$ARCH/boot/Image")
-        else
-            echo "run-riscv-qemu (error): you need to define QEMU_KERNEL with the Image to be used."
+EXTRA=""
+KERNEL=""
+DISK=""
+while [[ $# -gt 0 ]]; do
+    case $1 in
+    -d | --disk)
+        if [ -z "$2" ]; then
+            echo "run-riscv-qemu (error): you have to provide a value for -d/--disk"
             exit 1
         fi
-        echo "run-riscv-qemu (info): using '$QEMU_KERNEL' as the Linux kernel Image."
-    else
-        echo "run-riscv-qemu (error): you need to define QEMU_KERNEL with the Image to be used."
-        exit 1
-    fi
-fi
 
-# Configurable variables.
-QEMU_CPU=${QEMU_CPU:-max}
-QEMU_SMP=${QEMU_SMP:-4}
-EXTRA=${EXTRA:-}
-
-# Cleanup older environments.
-rm -rf "$BUSYBOX_SRC/initramfs/home"
-
-while [[ $# -gt 0 ]]; do
-    case $1 in
+        DISK="$2"
+        shift 2
+        ;;
     -g | --gdb)
         EXTRA="-s -S"
         shift
@@ -43,14 +24,26 @@ while [[ $# -gt 0 ]]; do
         SHOW_HELP=1
         shift
         ;;
+    -k | --kernel)
+        if [ -z "$2" ]; then
+            echo "run-riscv-qemu (error): you have to provide a value for -k/--kernel"
+            exit 1
+        fi
+
+        KERNEL="$2"
+        shift 2
+        ;;
     -*)
         echo "run-riscv-qemu (error): unknown option '$1'."
         exit 1
         ;;
     *)
-        mkdir -p "$BUSYBOX_SRC/initramfs/home/$(whoami)"
-        cp "$1" "$BUSYBOX_SRC/initramfs/home/$(whoami)/"
-        shift # past argument
+        if [ ! -z "$BUSYBOX_SRC" ]; then
+            mkdir -p "$BUSYBOX_SRC/initramfs/home/$(whoami)"
+            cp "$1" "$BUSYBOX_SRC/initramfs/home/$(whoami)/"
+        fi
+
+        shift
         ;;
     esac
 done
@@ -58,24 +51,67 @@ done
 # Print the show message if needed.
 if [ -n "$SHOW_HELP" ]; then
     cat <<HERE
-usage: run-riscv-qemu.sh [OPTIONS]
+usage: run-riscv-qemu.sh [OPTIONS] [files]
 
 Run QEMU/KVM tailored to my needs for testing the Linux Kernel.
+  -d, --disk          Path to the disk to be passed into QEMU.
+  -g, --gdb           Wait for a GDB connection.
+  -h, --help          Show this message.
+  -k, --kernel        Path to the Linux kernel image to be used.
 
-  -g, --gdb             Wait for a GDB connection.
-  -h, --help            Show this message.
+After the options you can pass paths to files you want to have inside of your
+/home directory (unless '-d/--disk' is defined).
+HERE
+    exit 0
+fi
+
+# If the $KERNEL argument has not been set, then guess one based on the current
+# working directory.
+if [ -z "$KERNEL" ]; then
+    if [ ! -z "$ARCH" ]; then
+        if [ -f "arch/$ARCH/boot/Image" ]; then
+            KERNEL=$(realpath "arch/$ARCH/boot/Image")
+        else
+            echo "run-riscv-qemu (error): you need to define QEMU_KERNEL with the Image to be used."
+            exit 1
+        fi
+        echo "run-riscv-qemu (info): using '$QEMU_KERNEL' as the Linux kernel Image."
+    else
+        echo "run-riscv-qemu (error): you need to define QEMU_KERNEL with the Image to be used."
+        exit 1
+    fi
+fi
 
-Environment variables that can be used the further configure the run:
+##
+# If the user provided a disk option, run QEMU with that disk in mind.
+
+if [ ! -z "$DISK" ]; then
+    qemu-system-riscv64 -machine virt -nographic \
+                        -cpu max -smp 4 -m 8G \
+                        -drive file="$DISK",format=qcow2,id=hd0 \
+                        -device virtio-net-device,netdev=usernet \
+                        -netdev user,id=usernet,hostfwd=tcp::22222-:22 \
+                        -kernel "$KERNEL" \
+                        -append nokaslr \
+                        -append ftrace_dump_on_oops \
+                        -append sysctl.kernel.panic_on_rcu_stall=1 \
+                        $EXTRA
 
-  - EXTRA: extra arguments to pass. Default: (empty).
-  - QEMU_CPU: CPU model to use (i.e. argument for '-cpu'). Default: 'max'.
-  - QEMU_SMP: number of cores (i.e. argument for '-smp'). Default: 4.
-HERE
     exit 0
 fi
 
 ##
-# Generate the initramfs.
+# No disk provided, let's generate an initramfs of our own run run in /dev/ram
+# with a tmpfs.
+
+# Enfore BUSYBOX_SRC.
+if [ -z "$BUSYBOX_SRC" ]; then
+    echo "run-riscv-qemu (error): you need to define BUSYBOX_SRC."
+    exit 1
+fi
+
+# Cleanup older environments.
+rm -rf "$BUSYBOX_SRC/initramfs/home"
 
 pushd "$BUSYBOX_SRC/initramfs"
 find . -print0 | cpio --null -o --format=newc | gzip -9 >../initramfs.cpio.gz
@@ -87,10 +123,10 @@ popd
 set -x
 
 qemu-system-riscv64 -machine virt -nographic \
-    -cpu "$QEMU_CPU" \
-    -m 8G \
-    -smp "$QEMU_SMP" \
-    -kernel "$QEMU_KERNEL" \
+    -cpu max -m 8G -smp 4 \
+    -device virtio-net-device,netdev=usernet \
+    -netdev user,id=usernet,hostfwd=tcp::22222-:22 \
+    -kernel "$KERNEL" \
     -initrd "$BUSYBOX_SRC/initramfs.cpio.gz" \
     -append "root=/dev/ram" \
     -append nokaslr \
-- 
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