Messages in this thread | | | Date | Wed, 20 Mar 2013 16:11:25 -0500 | From | William Hubbs <> | Subject | Re: [PATCH] init: fix name of root device in /proc/mounts |
| |
On Wed, Mar 20, 2013 at 02:03:20AM -0500, Rob Landley wrote: > On 03/19/2013 07:20:17 PM, William Hubbs wrote: > > On Tue, Mar 19, 2013 at 04:17:11PM -0700, H. Peter Anvin wrote: > > > On 03/19/2013 03:28 PM, William Hubbs wrote: > > > > The issue is that /dev/root appears in /proc/mounts if you do not > > > > boot with an initramfs, but /dev/root is not a device node. In the > > > > past, udev created a symbolic link from /dev/root to the > > > > appropriate block device, but it does not do this any longer. > > Also, > > > > devtmpfs does not create this symbolic link. > > > > > > > > This is causing bugs with software that depends on the existence > > > > of /dev/root [2] for example. > > > > > > Seems okay to me, although even better would be to use the udev name > > > of the device in question. > > > > I'm not following what you mean. > > > > The problem is that "/dev/root" should not be in /proc/mounts, > > since there is always another entry that points to the root > > file system. > > What gave you that idea? > > wget http://landley.net/aboriginal/bin/system-image-i686.tar.bz2 > extract it and ./run-emulator.sh and in there: > > (i686:1) /home # cat /proc/mounts > rootfs / rootfs rw 0 0 > /dev/root / squashfs ro,relatime 0 0 > proc /proc proc rw,relatime 0 0 > sys /sys sysfs rw,relatime 0 0 > dev /dev devtmpfs rw,relatime,size=63072k,nr_inodes=15768,mode=755 0 0 > dev/pts /dev/pts devpts rw,relatime,mode=600 0 0 > /tmp /tmp tmpfs rw,relatime 0 0 > /home /home tmpfs rw,relatime 0 0 > > Userspace can totally determine what /dev/root points to, I made mdev > do it in 2006 (udev started doing so shortly thereafter). Busybox git > commit a7e3d052.:4
There are situations where it doesn't work though -- suppose that root is btrfs for example.
Also, the other message that answered you is correct, the udev maintainers say we should not be relying on /dev/root at all so to make it work distro packagers have to add a rule themselves.
Kay,
if you are reading, canyou jump in and explain why /dev/root is a bad idea?
Thanks,
William
[unhandled content-type:application/pgp-signature] | |