Finding/setting nvalias (nvram) OBP settings from a running Solaris O/S


Using the command eeprom (1m) while in the Solaris O/S on SPARC platforms has been a useful way to view and set OBP parameters without bringing the entire machine offline and down to the ok prompt.

Unfortunately, eeprom does not show nvalias definitions. These are most often used to specify root and mirror O/S boot devices. For clarity, these are then plugged into the boot-device and diag-device OBP variables. (diag-device is the OBP variable used to boot the machine when the physical or virtual keyswitch is set to “diag mode.”)

Luckly, prtconf -vp will give you this information once you do a little bit of digging…

*$ prtconf -vp*

*....*

*<snip>*

*....*

*Node 0xf022d030
ttya-rts-dtr-off: 'false'
ttya-ignore-cd: 'true'
local-mac-address?: 'true'
fcode-debug?: 'false'
scsi-initiator-id: '7'
oem-logo:
oem-logo?: 'false'
oem-banner:
oem-banner?: 'false'
ansi-terminal?: 'true'
screen-#columns: '80'
screen-#rows: '34'
ttya-mode: '9600,8,n,1,-'
output-device: 'virtual-console'
input-device: 'virtual-console'
auto-boot-on-error?: 'false'
load-base: '16384'
auto-boot?: 'true'
network-boot-arguments:
boot-command: 'boot'
boot-file:
boot-device: 'disk net'
use-nvramrc?: 'false'
nvramrc:
security-mode: 'none'
security-password:
security-#badlogins: '0'
verbosity: 'min'
diag-switch?: 'true'
error-reset-recovery: 'boot'
name: 'options'*

*Node 0xf022d0a8
ttya: '/pci@7c0/pci@0/pci@1/pci@0/isa@2/serial@0,3f8'
nvram: '/virtual-devices/nvram@3'
net3: '/pci@7c0/pci@0/pci@2/network@0,1'
net2: '/pci@7c0/pci@0/pci@2/network@0'
net1: '/pci@780/pci@0/pci@1/network@0,1'
net0: '/pci@780/pci@0/pci@1/network@0'
net: '/pci@780/pci@0/pci@1/network@0'
ide: '/pci@7c0/pci@0/pci@1/pci@0/ide@8'
cdrom: '/pci@7c0/pci@0/pci@1/pci@0/ide@8/cdrom@0,0:f'
disk3: '/pci@780/pci@0/pci@9/scsi@0/disk@3'
disk2: '/pci@780/pci@0/pci@9/scsi@0/disk@2'
disk1: '/pci@780/pci@0/pci@9/scsi@0/disk@1'
disk0: '/pci@780/pci@0/pci@9/scsi@0/disk@0'
disk: '/pci@780/pci@0/pci@9/scsi@0/disk@0'
scsi: '/pci@780/pci@0/pci@9/scsi@0'
virtual-console: '/virtual-devices/console@1'
name: 'aliases'

*....*

*<snip>*

*....*

The first thing we need to do is to set the “use-nvramrc = true” OBP variable so our modifications will be used. Viewing parameters with eeprom (1m) is accessible to regular users. Modifying these values requires root privileges.

*$ eeprom use-nvramrc?
use-nvramrc?=false*

Since its false..

*# eeprom use-nvramrc?=true*

To verify..

*$ eeprom use-nvramrc?*

*use-nvramrc?=true*

Awesome. Step 1 down.

Next, we define the device we want to use. First, figure out what your root and mirror devices are.

*$ df -h /
Filesystem size used avail capacity Mounted on
/dev/md/dsk/d10 32G 22G 9.4G 70% /bin /boot /cdrom /core /dev /esx /etc /hom /home /initrd.img /lib /lib32 /lib64 /media /mnt /opt /proc /root /run /sbin /snap /srv /sys /tmp /usr /var /vmlinuz

*$ metastat -p d10
d10 -m d11 d12 1
d11 1 1 c0t0d0s0
d12 1 1 c0t1d0s0*

So we’ve got an encapsulated SVM root file system. Lets find the device paths for c0t0d0 and c0t1d0 under the /devices name space.

*$ ls -l /dev/dsk/c0t0d0s0
lrwxrwxrwx 1 root root 49 Feb 6 11:06 /dev/dsk/c0t0d0s0 ->
../../devices/pci@780/pci@0/pci@9/scsi@0/sd@0,0:a*

*$ ls -l /dev/dsk/c0t1d0s0
lrwxrwxrwx 1 root root 49 Jan 11 2007 /dev/dsk/c0t1d0s0 ->
../../devices/pci@780/pci@0/pci@9/scsi@0/sd@1,0:a*

Ok.. so removing the “/devices” from the path (since that’s just a Solaris name space) and the trailing “a” gives us the following….

/pci@780/pci@0/pci@9/scsi@0/sd@0,0

/pci@780/pci@0/pci@9/scsi@0/sd@1,0

(Side note… the “a” stands for slice 0. Slice 1 would have a “b”, slice 2 would have a “c”, etc. You can see an example of this by issuing a $ ls -l /dev/dsk/c0t0d0s1. That’s why when you boot off of cdrom, you’ll see a trailing “f”. By default, its looking for boot strap information on slice 6!)

We can confirm this by grepping for the two above paths into /etc/path_to_inst

*$ grep '/pci@780/pci@0/pci@9/scsi@0/sd@[0-1],0' /etc/path_to_inst
"/pci@780/pci@0/pci@9/scsi@0/sd@0,0" 1 "sd"
"/pci@780/pci@0/pci@9/scsi@0/sd@1,0" 3 "sd"*

Sweet. Step 2 down.

Next, lets assign an alias of “rootdisk” to the first device and “rootmirror” to the second. Replace the two characters “sd” with the word “disk”.

*# eeprom nvramrc="devalias rootdisk
/pci@780/pci@0/pci@9/scsi@0/disk@0,0 devalias rootmirror
/pci@780/pci@0/pci@9/scsi@0/disk@1,0"*

While we’re at it, lets change our boot device to point to rootdisk and rootmirror.

*# eeprom boot-device="rootdisk rootmirror"*
The OBP variable nvramrc a placeholder for values that haven't been
committed into the NVRAM. Upon the next reboot, the nvaliasrc variable
will be commited into NVRAM. Lets see this in action. The whole point of
this article is so we didn't have to bounce the machine, but just to
prove this is how it works lets see it anyways.

*# halt
syncing file systems... done
Program terminated
{0} ok*

*{0} ok printenv nvramrc
nvramrc = devalias rootdisk /pci@780/pci@0/pci@9/scsi@0/disk@0,0
devalias rootmirror /pci@780/pci@0/pci@9/scsi@0/disk@1,0*

So there’s our value that we stuck into nvramrc.

Our modifications haven’t appeared under devalias yet because a complete boot cycle is needed before the contents of nvramrc gets committed into NVRAM…

*{0} ok devalias
ttya /pci@7c0/pci@0/pci@1/pci@0/isa@2/serial@0,3f8
nvram /virtual-devices/nvram@3
net3 /pci@7c0/pci@0/pci@2/network@0,1
net2 /pci@7c0/pci@0/pci@2/network@0
net1 /pci@780/pci@0/pci@1/network@0,1
net0 /pci@780/pci@0/pci@1/network@0
net /pci@780/pci@0/pci@1/network@0
ide /pci@7c0/pci@0/pci@1/pci@0/ide@8
cdrom /pci@7c0/pci@0/pci@1/pci@0/ide@8/cdrom@0,0:f
disk3 /pci@780/pci@0/pci@9/scsi@0/disk@3
disk2 /pci@780/pci@0/pci@9/scsi@0/disk@2
disk1 /pci@780/pci@0/pci@9/scsi@0/disk@1
disk0 /pci@780/pci@0/pci@9/scsi@0/disk@0
disk /pci@780/pci@0/pci@9/scsi@0/disk@0
scsi /pci@780/pci@0/pci@9/scsi@0
virtual-console /virtual-devices/console@1
name aliases*

Lets bounce the box so the contents of nvramrc are committed into NVRAM. (

*{0} ok boot rootdisk

*SC Alert: Host System has Reset*

*SC Alert: Host system has shut down.
..

*...*

*Sun Fire T200, No Keyboard
Copyright 2006 Sun Microsystems, Inc. All rights reserved.
OpenBoot 4.25.0, 32760 MB memory available, Serial #XXXXXXX
Ethernet address 0:14:4f:xx:xx:xx, Host ID: xxxxxxxx*

***Rebooting with command: boot rootdisk**
Boot device: **/pci@780/pci@0/pci@9/scsi@0/disk@0,0** File and args:
Loading ufs-file-system package 1.4 04 Aug 1995 13:02:54.
FCode UFS Reader 1.12 00/07/17 15:48:16.
Loading: /platform/SUNW,Sun-Fire-T200/ufsboot
Loading: /platform/sun4v/ufsboot
SunOS Release 5.10 Version Generic_127111-05 64-bit
Copyright 1983-2007 Sun Microsystems, Inc. All rights reserved.*
Sure enough, once the box is back online, prtconf -vp found our
modifications committed into NVRAM.

*$ prtconf -vp*

*...*

*<snip>*

*...*

*Node 0xf022d0a8
**rootmirror: '/pci@780/pci@0/pci@9/scsi@0/disk@1'
rootdisk: '/pci@780/pci@0/pci@9/scsi@0/disk@0'**
ttya: '/pci@7c0/pci@0/pci@1/pci@0/isa@2/serial@0,3f8'
nvram: '/virtual-devices/nvram@3'
net3: '/pci@7c0/pci@0/pci@2/network@0,1'
net2: '/pci@7c0/pci@0/pci@2/network@0'
net1: '/pci@780/pci@0/pci@1/network@0,1'
net0: '/pci@780/pci@0/pci@1/network@0'
net: '/pci@780/pci@0/pci@1/network@0'
ide: '/pci@7c0/pci@0/pci@1/pci@0/ide@8'
cdrom: '/pci@7c0/pci@0/pci@1/pci@0/ide@8/cdrom@0,0:f'
disk3: '/pci@780/pci@0/pci@9/scsi@0/disk@3'
disk2: '/pci@780/pci@0/pci@9/scsi@0/disk@2'
disk1: '/pci@780/pci@0/pci@9/scsi@0/disk@1'
disk0: '/pci@780/pci@0/pci@9/scsi@0/disk@0'
disk: '/pci@780/pci@0/pci@9/scsi@0/disk@0'
scsi: '/pci@780/pci@0/pci@9/scsi@0'
virtual-console: '/virtual-devices/console@1'
name: 'aliases'*

If you follow this procedure closely, you don’t have to bounce the box to make this modification – but keep in mind that messing around with these OBP variables especially boot-device without testing can leave your machine in a state for some other poor administrator to figure out which disk is your real boot-device. I take no responsibility for what you do with your OBP modifications. =)

This article was posted by Matty on 2008-03-21 15:23:00 -0400 EDT