Use buildroot qemu

README.md

@@ -4,7 +4,7 @@ Run one command, get into QEMU Buildroot BusyBox with several minimal Linux kern
 
 Usage:
 
-    sudo apt-get install qemu
+    sudo apt-get build-dep qemu
     ./run
 
 First build will take a while (GCC, Linux kernel).

buildroot_config_fragment

@@ -15,13 +15,10 @@ BR2_PACKAGE_HOST_GDB_SIM=y
 BR2_PACKAGE_HOST_GDB_TUI=y
 
 ## QEMU.
-# Buildroot can also build QEMU, but it does not have SDL support,
-# so you have to mess around with a VNC, so let's not use that for now.
-# Someone should patch this, and add a SDL support option to the QEMU package! :-)
-#BR2_PACKAGE_HOST_QEMU=y
-#BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE=n
-#BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE=y
-#BR2_PACKAGE_HOST_QEMU_VDE2=y
+BR2_PACKAGE_HOST_QEMU=y
+BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE=n
+BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE=y
+BR2_PACKAGE_HOST_QEMU_VDE2=y
 
 ## Target GDB
 # This is preparation for target GDB / gdbserver.

buildroot_patches/README.md

@@ -0,0 +1,5 @@
+# Buildroot patches
+
+Ideally, this directory should be empty, and we should use only built-in Buildroot configuration mechanisms.
+
+But alas, life is sometimes not ideal.

buildroot_patches/qemu_sdl.patch

@@ -0,0 +1,12 @@
+diff --git a/package/qemu/qemu.mk b/package/qemu/qemu.mk
+index 66efcba..1e09ea4 100644
+--- a/package/qemu/qemu.mk
++++ b/package/qemu/qemu.mk
+@@ -74,6 +74,7 @@ HOST_QEMU_SYS_ARCH ?= $(HOST_QEMU_ARCH)
+ 
+ ifeq ($(BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE),y)
+ HOST_QEMU_TARGETS += $(HOST_QEMU_SYS_ARCH)-softmmu
++HOST_QEMU_OPTS += --enable-sdl --with-sdlabi=2.0
+ HOST_QEMU_OPTS += --enable-system --enable-fdt
+ HOST_QEMU_DEPENDENCIES += host-dtc
+ else

run

@@ -19,10 +19,15 @@ case "$arch" in
     defconfig=qemu_arm_versatile_defconfig
     ;;
 esac
+for p in ../buildroot_patches/*.patch; do
+    patch -N -p1 <"../buildroot_patches/${p}" || :
+done
 make BR2_EXTERNAL="$(pwd)/../kernel_module" "$defconfig"
-# Can't get rid of this for now.
+# TODO Can't get rid of this for now.
 # http://stackoverflow.com/questions/44078245/is-it-possible-to-use-config-fragments-with-buildroots-config
 cat ../buildroot_config_fragment >> .config
+# TODO there is no make host_qemu-rebuild ?
+rm -f output/build/host-qemu-2.7.0/.stamp_built
 env -u LD_LIBRARY_PATH make BR2_JLEVEL="$(($(nproc) - 2))" kernel_module-rebuild all
 cd ..
 ./runqemu "$@"

runqemu

@@ -42,9 +42,7 @@ case "$arch" in
       if $kgdb; then
         extra_append="$extra_append kgdboc=ttyS0,115200"
       fi
-      # If we turn on buildroot host QEMU some day.
-      #cmd="./buildroot/output/host/usr/bin/qemu-system-x86_64 \
-      cmd="qemu-system-x86_64 \
+      cmd="./buildroot/output/host/usr/bin/qemu-system-x86_64 \
         -M pc \
         -append 'root=/dev/vda $extra_append' \
         -drive file=${images_dir}/rootfs.ext2,if=virtio,format=raw \