Arm backend: Remove output buffering when running Corstone FVP with tee (#8821)

Arm backend: Remove output buffering when running FVP with tee

This improves the log output feedback when running the FVP so you
don't have to wait for slow models without any output.

Signed-off-by: Zingo Andersen <[email protected]>

Author: zingo

backends/arm/scripts/run_fvp.sh

@@ -69,10 +69,21 @@ echo "Running ${elf_file} for ${target} run with FVP:${fvp_model} num_macs:${num
 echo "WARNING: Corstone FVP is not cycle accurate and should NOT be used to determine valid runtime"
 echo "--------------------------------------------------------------------------------"
 
+# Check if stdbuf is intalled and use stdbuf -oL together with tee below to make the output
+# go all the way to the console more directly and not be buffered
+
+if hash stdbuf 2>/dev/null; then
+    nobuf="stdbuf -oL"
+else
+    nobuf=""
+fi
+
 log_file=$(mktemp)
 
+
+
 if [[ ${target} == *"ethos-u55"*  ]]; then
-    ${fvp_model}                                            \
+    ${nobuf} ${fvp_model}                                            \
         -C ethosu.num_macs=${num_macs}                      \
         -C mps3_board.visualisation.disable-visualisation=1 \
         -C mps3_board.telnetterminal0.start_telnet=0        \
@@ -82,7 +93,7 @@ if [[ ${target} == *"ethos-u55"*  ]]; then
         --timelimit ${timeout} 2>&1 | tee ${log_file} || true # seconds
     echo "[${BASH_SOURCE[0]}] Simulation complete, $?"
 elif [[ ${target} == *"ethos-u85"*  ]]; then
-    ${fvp_model}                                            \
+    ${nobuf} ${fvp_model}                                            \
         -C mps4_board.subsystem.ethosu.num_macs=${num_macs} \
         -C mps4_board.visualisation.disable-visualisation=1 \
         -C vis_hdlcd.disable_visualisation=1                \