I found this works
$./adb shell
$su
mount -o rw,remount rootfs /
chmod 777 /mnt/sdcard
exit
Source: http://www.coderanch.com/t/611842/Android/Mobile/Android-emulator-sdcard-writable
I found this works
$./adb shell
$su
mount -o rw,remount rootfs /
chmod 777 /mnt/sdcard
exit
Source: http://www.coderanch.com/t/611842/Android/Mobile/Android-emulator-sdcard-writable