Messages in this thread | | | Date | Wed, 27 Oct 2004 14:58:08 -0400 (EDT) | From | linux-os <> | Subject | Re: loopback on block device |
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On Wed, 27 Oct 2004, Lei Yang wrote:
> Hello, > > Here is a question for loopback device. As far as I understand, the loopback > device is used to mount files as if they were block devices. > > Then Why I could do "losetup -e XOR /dev/loop0 /dev/ram0" ? Notice that ram0 > is not mounted anywhere and does not have a filesystem on it. I've tried that > command and there seems to be no error. I got confused and looked into > loop.c, it seems to me that a loopback device should be associated with a > "backing file", why would it work on a block device anyway? > > I'd appreciate your comments greatly! > > TIA, > Lei >
`man losetup` You just set up the loop device to enable encryption on /dev/ram0. /dev/ram0 is a "file". It's a special-file, but a file nevertheless. It can contain a file-system, therefore act as a RAM disk, but it doesn't have to.
In principle, you could make an encrypted file-system in which you couldn't even know what kind of file- system it was, without an encryption key.
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