arm/qemu-armv7a: add discard-data-on in rpproxy_ivshmem launch command

add discard-data=on in proxy launch command, so the proxy side
will clean the share memory to make sure that the shared memory is clean
every time server and proxy are started.

Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>

Documentation/platforms/arm/qemu/boards/qemu-armv7a/index.rst

@@ -107,7 +107,7 @@ Steps for Using NuttX as IVSHMEM host and guest
   b. Start rpproxy_ivshmem::
 
       $ qemu-system-arm -cpu cortex-a7 -nographic -machine virt,highmem=off \
-        -object memory-backend-file,id=shmmem-shmem0,mem-path=/dev/shm/ivshmem0,size=4194304,share=yes \
+        -object memory-backend-file,discard-data=on,id=shmmem-shmem0,mem-path=/dev/shm/ivshmem0,size=4194304,share=yes \
         -device ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,addr=0xb \
         -kernel proxy/nuttx -nographic
 

boards/arm/qemu/qemu-armv7a/configs/rpserver_ivshmem/defconfig

@@ -29,7 +29,7 @@ CONFIG_ARM_PSCI=y
 CONFIG_ARM_SEMIHOSTING_HOSTFS=y
 CONFIG_ARM_THUMB=y
 CONFIG_BCH=y
-CONFIG_BLK_RPMSG=y
+CONFIG_BLK_RPMSG_SERVER=y
 CONFIG_BOARDCTL_POWEROFF=y
 CONFIG_BOARD_LATE_INITIALIZE=y
 CONFIG_BUILTIN=y
@@ -42,7 +42,7 @@ CONFIG_DEBUG_PCI_INFO=y
 CONFIG_DEBUG_PCI_WARN=y
 CONFIG_DEBUG_SYMBOLS=y
 CONFIG_DEVICE_TREE=y
-CONFIG_DEV_RPMSG=y
+CONFIG_DEV_RPMSG_SERVER=y
 CONFIG_DEV_SIMPLE_ADDRENV=y
 CONFIG_EXAMPLES_HELLO=y
 CONFIG_EXAMPLES_RPMSGSOCKET=y