Re: block devices

[Samuel Thibault]

Hello,

Fabio Gonzalez, le Wed 10 Oct 2012 05:35:35 -0300, a écrit :
> When we use the Linux kernel, mount the application says it can not
> mount devices that are not block devices.

Yes, because filesystems usually need to go back & forth in the device
data, which is usually not permitted by non-block deviceS.

> The documents [1] serves to allow mount it?
> [1]:http://www.gnu.org/software/hurd/hacking-guide/hhg.html#An-Example-using-trivfs
> 
Almost: see in the file_operations structure: the seek operation is
missing.  That one would be needed to allow mounting a filesystem stored
on the device. ioctl, mmap and flush might have to be implemented too.

> The Linux version, this basically ready, but does not work well ([2]).
> RMS said that when we accepted my software ask me to suit it to Hurd.
> [2]:http://git.savannah.gnu.org/cgit/fcrypt.git/tree/src/kernel/fcrypt_module.c

Ideally yes, indeed, and trivfs is the right approach (that's actually
how other block devices are implemented in the Hurd).

Samuel