ext3 labels and devfsd

acid_kewpie · 05-12-2003, 06:23 AM

after upgrading a bunch of system packages on gentoo, it wanted to create a new fstab, which contained lines like...

Code:

/dev/BOOT               /boot           ext2            noauto,noatime          1 1
/dev/ROOT               /               xfs             noatime                 0 0
/dev/SWAP               none            swap            sw                      0 0

presumably this is saying that it is using the label of the ext3 filesystem as a pseudonym to the actual ide device.... i can't find anything that says how to set this up. i do have a "root" setup by devfs, but i'm assuming that it's not based on the label, just the fact that it IS root (and only coincidentally the same as the label name). I am using the labels in fstab at the moment, it's just out of interest if anyone knows how to create these automatically, and if i am actually assuming this setup correctly.

dorian33 · 05-12-2003, 02:26 PM

AFAIR when you are creating partition - let's say hda3 - with fdisk you can name it as let's say MYDATA. Then MYDATA becames the equivalent name for hda3. Generally it is more flexible (but I am not using it) since you have not to remember that hda3 contains your data - the label can recall it to you.

acid_kewpie · 05-12-2003, 03:39 PM

yes i'm aware of that, what i mean is that devfs appears to have actually created a /dev/ entry based on the label value...

MasterC · 05-12-2003, 03:40 PM

Is it an actual block device, or is it simply a symlink?

Cool

acid_kewpie · 05-12-2003, 03:43 PM

well devfs is all symlinks really, just like hdb is a symlink to ide/host0/bus0/target1/lun0/disc... i don't know if this is what they say it can do is is simply meant to mean "replace this with the real values", or they are implying that that is what the partitions are labelled as...

DavidPhillips · 05-12-2003, 04:16 PM

This is an example file, I replaced them with the actual symlink

/dev/hda3

etc...

That's what I perceived it to be anyway.

moses · 05-13-2003, 01:18 AM

Not sure if you know about e2label, which allows you to change the label of an e2fs-type partition, but it appears to me that devfsd only makes a symlink for the root partition (presumably by reading the /etc/fstab). My root partition's label is now "root_disk", and there is still only a /dev/root, not a /dev/root_disk.

acid_kewpie · 05-13-2003, 04:19 AM

yeah i have a /dev/root i guess that is nothing to do with the e2label at all... would be a logical feature i'd think. thanks

moses · 05-13-2003, 12:14 PM

It appears as though the /dev/root is a backward compatibility of devfs to the old, crappy style of /dev.
man devfsd:

Quote:

As part of its setup phase devfsd creates certain symbolic
links which are compiled into the code. These links are
required by /usr/src/linux/Documentation/devices.txt. This
behaviour may change in future revisions.

In /usr/src/linux/Documentation/devices.txt:

Quote:

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/mouse mouse port symbolic Current mouse device
/dev/tape tape device symbolic Current tape device
/dev/cdrom CD-ROM device symbolic Current CD-ROM device
/dev/cdwriter CD-writer symbolic Current CD-writer device
/dev/scanner scanner symbolic Current scanner device
/dev/modem modem port symbolic Current dialout device
/dev/root root device symbolic Current root filesystem
/dev/swap swap device symbolic Current swap device

acid_kewpie · 05-13-2003, 12:21 PM

interesting. i don't know if it'd be at all useful, but very possible....

thamarsol · 05-15-2003, 01:57 PM

I all!!
So, I'm a total newbie here and I'm trying to install some tools on Linux, and I receive the following message:
Please set a symlink to /usr/bin/perl in /usr/local/bin/perl and rerun installation.

I know it must be something trivial but still don't want to mess up things.
Thanks for your help

DavidPhillips · 05-15-2003, 02:07 PM

run this command from some shell

ln -s /usr/bin/perl /usr/local/bin/perl