Current losetup supports creating RO loops: the set_loop has an argument that
requests and returns the open mode, and the function also checks if the
filesystem the file resides on is mounted read-only.
But there is no way to specify the RO mode from the command line. The attached
patch adds a new -r option.
Created attachment 139067 [details]
patch adding -r option to losetup
FC6 seems like better target for this feature. Thanks for your patch.