[BusyBox] Serious bug in find_mount_point.c

[Rob Landley]

On Saturday 12 March 2005 08:53 pm, Rainer Weikusat wrote:
> Rob Landley <rob at landley.net> writes:
> > On Friday 11 March 2005 05:21 pm, Rainer Weikusat wrote:
> >> Brent Roman <brent at mbari.org> writes:
> >> > Guess what?
> >> >
> >> > The fedora 2 box has no /dev/root !!
> >>
> >> Hmm ... why do you think it should?
> >
> > Because it's in the linux device list?
> >
> > http://www.lanana.org/docs/device-list/devices-2.6+.txt
> >
> > Block major 4, minor 0.
>
>  4 block	Aliases for dynamically allocated major devices to be used
> 		when its not possible to create the real device nodes
> 		because the root filesystem is mounted read-only.
>
>                 0 = /dev/root
>
> [...]
>
>      	Locally defined links
>
> 	The following links may be established locally to conform to
> 	the configuration of the system.  This is merely a tabulation
>                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 	of existing practice, and does not constitute a
>         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 	recommendation.  However, if they exist, they should have the
>         ^^^^^^^^^^^^^^^
> 	following uses.
>
> [...]
>
> 	/dev/root	root device	symbolic	Current root filesystem
> 	/dev/swap	swap device	symbolic	Current swap device

I.E. if you don't want to use the block device to what the kernel autodetected 
on the way up, you can make it a symlink to your real device instead.

As for this being "just a convention":

knoppix at ttyp1[linux-2.6.11.3]$ grep "\/dev\/root" init/*
init/do_mounts.c:       create_dev("/dev/root", ROOT_DEV, NULL);
init/do_mounts.c:           do_mount_root("/dev/root", "nfs", root_mountflags, 
data) == 0)
init/do_mounts.c:       fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
init/do_mounts.c:       create_dev("/dev/root", ROOT_DEV, root_device_name);
init/do_mounts.c:       mount_block_root("/dev/root", root_mountflags);
init/do_mounts_initrd.c:        create_dev("/dev/root.old", Root_RAM0, NULL);
init/do_mounts_initrd.c:        mount_block_root("/dev/root.old", 
root_mountflags & ~MS_RDONLY);
init/do_mounts_initrd.c:                int fd = sys_open("/dev/root.old", 
O_RDWR, 0);
init/do_mounts_rd.c:    create_dev("/dev/root", ROOT_DEV, root_device_name);
init/do_mounts_rd.c:    return rd_load_image("/dev/root");

Can't say I've looked into it too closely since 2.4, though.  That area's 
changed a bit...

Rob