Check whether sd card is presenting and mounting as RO, before do the real remount

platform/kobo/koreader.sh

@@ -80,8 +80,12 @@ if [ ! -n "${PLATFORM}" ] ; then
 fi
 # end of value check of PLATFORM
 
-# Remount SD to RW, ignore errors since we may not have sd card
-mount -o remount,rw /mnt/sd || true
+grep ' /mnt/sd ' /proc/mounts | grep 'ro'
+# Remount SD to RW if it's RO
+if [ $? -eq 0 ]
+then
+    mount -o remount,rw /mnt/sd
+fi
 
 ./reader.lua "${args}" 2> crash.log