这是cedega中关于error = 21的说明，
Exec (error = 21)
The version of mount that comes with some distributions now run with the noexec option unless otherwise specified. Running games from a partition mounted with noexec can cause an error = 21 message.
To fix this issue, edit the /etc/fstab and modify the partition line by removing the noexec option and adding the exec switch to the mount options.
/dev/hda1 / ext3 errors=remount-ro,no-exec,defaults 0 1
/dev/hda1 / ext3 errors=remount-ro,exec,defaults 0 1
If neither exec nor no-exec appears in the line it is recommended that you add exec to ensure that the partition can be used by Cedega.
To remount the partition run:
mount -o remount /
sda5 /etc/sda5 /windows/sda5 vfat auto,user,iocharacter=utf8 0 0