use grub2-install --no-nvram on PowerNV system

[schabrolles]

Relax-and-Recover (ReaR) Pull Request Template

Please fill in the following items before submitting a new pull request:

Pull Request Details:

• Type: Bug Fix

• Impact: Normal

• Reference to related issue (URL): Rescue system start hangup for RHEL 7.4 on PPC 64 LE Power8 BareMetal (Petitboot v1.4.4) #1710
  https://www.suse.com/fr-fr/support/update/announcement/2017/suse-ru-20170617-1/

• How was this pull request tested?
  Tested on RHEL 7 BareMetal (PowerNV) [ReaR Backup + restore with NFS+PXE]
  Tested on RHEL 7 KVM Guest for non-regression test [ReaR Backup + restore with NFS+PXE]
  Tested on RHEL 7 LPAR (PowerVM) for non-regression test [ReaR Backup + restore with NFS+PXE]

• Brief description of the changes in this pull request:
  Problem description: grub2-install failed on PowerNV (BareMetal System).
  grub2-install for power (ppc64le) always try to update firmware boot order during grub2-install by using ofpathname command. Unfortunatly, this ofpathname command is not supported on BareMetal system (PowerNV). (https://www.suse.com/fr-fr/support/update/announcement/2017/suse-ru-20170617-1/).
  Using --no-nvram grub2-install option is a workaround for PowerNV system.

[schabrolles]

@jsmeix , @gdha I just asking for a quick review before merging. It is a pure POWER change and I know you don"t have such kind of system to validate. But you always have good feedback ;)

[jsmeix]

I cannot reproduce this condition on my x86_64 system (there is no 'platform' in /proc/cpuinfo)
but what I can reproduce there is e.g.:

# awk '/vendor_id/ {print $NF}' < /proc/cpuinfo
GenuineIntel
GenuineIntel
GenuineIntel
GenuineIntel
GenuineIntel
GenuineIntel
GenuineIntel
GenuineIntel

I get 8 lines because I have a 2 CPUs with 4 cores each
but when there is more than one line found
the condition does no longer result true:

# if [[ $( awk '/vendor_id/ {print $NF}' < /proc/cpuinfo ) == GenuineIntel ]] ; then echo Y ; else echo N ; fi
N

Bottom line:
The current condition is not fail-safe against multiple 'platform' lines.

Usually I use an artificial bash array to get a field at a know position
out of the first line of possibly several output lines like:

# vendor_id_lines=( $( grep '^vendor_id' /proc/cpuinfo ) )

# for element in "${vendor_id_lines[@]}" ; do echo "'$element'" ; done
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'
'vendor_id'
':'
'GenuineIntel'

# if test "${vendor_id_lines[2]}" = "GenuineIntel" ; then echo Y ; fi
Y

But this only works when the wanted value
is at a known fixed position/index in the array.
E.g. it cannot be used to test for one of the many CPU flags.

[schabrolles]

@jsmeix ,

on Power, platform is printed only one time at the end:

processor	: 0
cpu		: POWER8 (raw), altivec supported
clock		: 2061.000000MHz
revision	: 2.0 (pvr 004d 0200)

[...]

processor	: 152
cpu		: POWER8 (raw), altivec supported
clock		: 2061.000000MHz
revision	: 2.0 (pvr 004d 0200)

timebase	: 512000000
platform	: PowerNV
model		: 8001-22C
machine		: PowerNV 8001-22C
firmware	: OPAL v3

We can also protect it by checking only the first line returned:

if [[ $(awk '/platform/ {print $NF}' < /proc/cpuinfo | head -n1 ) == PowerNV ]] 

[jsmeix]

@schabrolles
feel free to implement it as you like.
When it can appear at most one time it is also o.k. as is.

[jsmeix]

Except my generic comment where I cannot know
if it may actually matter in this case
it looks o.k. from plain looking at the code.