Bug 74750 – baselayout /sbin/rc should call "dmsetup mknodes" in the udev case

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Andreas Jellinghaus 2004-12-17 07:21:10 UTC]

if baselayout /sbin/rc does the udev case a new /dev is created
and populated by udev. udev however only created /dev/mapper/control
and ignores other dm* devices. In case a initrd was used to setup
some device mapping (e.g. a crypt layer for /), then a device for
that mapping should be created. if you could check in /sbin/rc
(in the udev branch) for dmsetup and - if it exists - call it with
"mknodes", then it will create such pre-configured mappings.

Reproducible: Always
Steps to Reproduce:
1. use some initrd to create a mapping before the real boot
2. make it boot gentoo, with new / and using kernel 2.6 with udev
3. look at the new /dev/mapper/ directory.

Actual Results:  
you will see only "control", but not the mapping you created in 
step 1. if you look at /initrd/dev (if you kept that), you will still 
see that it was created ok in the initrd. 

Expected Results:  
check for dmsetup and call "dmsetup mknodes" which will read the kernel 
information on configured mappings and create appropriate devices if 
missing.

[Comment 1 Richard Westwell 2005-04-22 05:07:23 UTC]

"dmsetup mknodes" is one way of doing things, although in a way your not letting udev set up the device nodes
which means if you want to create symlinks as part of the udev rule (e.g. for evms) you won't be able to via udev

another way is to use a later version of dmsetup later than 1.00.20 (1.00.21 is the nearest but is currently masked)
dmsetup -j <major> -m <minor> will identify a device-mapper table entry name
which you can then fit in as part of the udev rules

in theory you'd be able to do stuff like create symlinks for lvm or evms, or even specific links for particular Hard disks (usefull for Raid)
http://forums.gentoo.org/viewtopic-t-263996-highlight-.html

[Comment 2 Andreas Jellinghaus 2005-04-22 09:39:52 UTC]

any solution is fine with me, if it provides the real system with a device
node for a dm mapping, that was already created in an initrd/initramfs.
I thought /sbin/rc is the proper place, but other options are fine with me,
too.

I'm sorry to tell you that I moved to a different OS in the meantime, so
I can't test any potential solution any more.

[Comment 3 SpanKY 2005-09-02 19:34:31 UTC]

this is in baselayout-1.11.13