kern/42799: LVM logical volumes fail to attach if 'pseudo-device dm' is compiled in th kernel

[hugo%barafranca.com@localhost]

>Number:         42799
>Category:       kern
>Synopsis:       LVM logical volumes fail to attach if 'pseudo-device dm' is 
>compiled in th kernel
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 12 13:50:00 +0000 2010
>Originator:     Hugo Silva
>Release:        5.99.24
>Organization:
>Environment:
NetBSD 5.99.24 (GENERIC) #1: Thu Feb 4 13:18:12 WET 2010 
root@:/usr/obj/sys/arch/amd64/compile/GENERIC amd64 
>Description:
# lvm vgchange -a y fails on a kernel with pseudo-device dm compiled in:

**** KERNEL WITH dm BUILTIN ****

# modstat|grep dm
dm driver builtin 0 - -

# lvm vgchange -a y
Found duplicate PV NocTy4YPiwyYjss19YXT0mIEb59EeLTi: using /dev/rwd2f not 
/dev/rwd0f
0 logical volume(s) in volume group "xenvg0" now active
0 logical volume(s) in volume group "sysvg0" now active

dmesg output:
Unable to attach pseudo device dm/xenvg0-arcturus_sys0
Unable to attach pseudo device dm/xenvg0-procyon_sys0
Unable to attach pseudo device dm/xenvg0-procyon_data0
Unable to attach pseudo device dm/xenvg0-capella_sys0
Unable to attach pseudo device dm/xenvg0-capella_data0
Unable to attach pseudo device dm/xenvg0-sirius_sys0
Unable to attach pseudo device dm/sysvg0-root
Unable to attach pseudo device dm/sysvg0-tmp
Unable to attach pseudo device dm/sysvg0-var
Unable to attach pseudo device dm/sysvg0-usr
Unable to attach pseudo device dm/sysvg0-home
Unable to attach pseudo device dm/sysvg0-swap
Unable to attach pseudo device dm/sysvg0-usrlocal

# head /dev/xenvg0/arcturus_sys0
head: /dev/xenvg0/arcturus_sys0: Device not configured 



**** GENERIC kernel (dm dynamically loaded as a module) ****

# lvm vgchange -a y
Found duplicate PV NocTy4YPiwyYjss19YXT0mIEb59EeLTi: using /dev/rwd2f not 
/dev/rwd0f
6 logical volume(s) in volume group "xenvg0" now active
7 logical volume(s) in volume group "sysvg0" now active

# modstat | grep dm
dm driver filesys 0 20968 -

# head /dev/xenvg0/arcturus_sys0
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Disk readNot a bootxx imageNo NetBSD 
partition`&#65533;&#65533;&#65533;
&#65533;&#65533;&#65533;&#65533;u&#65533;a&#65533;U&#65533;WEV&#65533;Xen
 Virtual ESD

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>How-To-Repeat:
Compile dm in the kernel and try to enable lvs.
>Fix:
modload dm

However and due to another problem, Xen kernels are unable to load modules at 
this point in time- rendering LVM useless with Xen (builtin dm dm results in 
the problem in this PR, and modload'ing does not work)