#1339 PR `merged`: Allow "grub PXE style" for non x86 platform.¶

Labels: enhancement, fixed / solved / done

schabrolles opened issue at 2017-05-02 08:58:¶

Some non x86 platform (like ppc64/ppc64le) does not support native PXE boot. Some document recommend to use GRUB as a PXE alternative. (https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Installation_Guide/chap-installation-server-setup.html#sect-network-boot-setup-ppc-grub2)

I would like to propose this possibility in ReaR as an addition to the standard PXE.

This alternative way to use "Grub PXE" server will be controlled by a new boolean variable : PXE_CONFIG_GRUB_STYLE
a New make_pxelinux_config_grub function to create the grub compatible boot menu.
Like PXE, when the client is looking at its MAC address or IP (in hex) on the config directory of the TFTP server. But file should be like this : grub.cfg-<MAC or IP>.
gethostip is part of syslinux (which is not available on PPC, may be some tool limited to x86...) I use a workaround based on printf when gethostip is not available

Here is an example of a local.conf

OUTPUT=PXE
OUTPUT_PREFIX_PXE=rear/$HOSTNAME
PXE_CONFIG_GRUB_STYLE=y
PXE_CONFIG_URL="nfs://10.7.19.177/var/lib/tftpboot/boot/grub2/powerpc-ieee1275"
PXE_CREATE_LINKS=IP
PXE_REMOVE_OLD_LINKS=y
PXE_TFTP_URL="nfs://10.7.19.177/var/lib/tftpboot"

BACKUP=NETFS
BACKUP_URL="nfs://10.7.19.177/rear"

tested successfully with RedHat 6, RedHat 7, Sles 11, Sles 12 on ppc64/ppc64le

Like usual, feedback/review welcomed

schlomo commented at 2017-05-02 09:12:¶

Nice addition. I was actually already thinking about switching to Grub2 for all our boot loader needs.

jsmeix commented at 2017-05-02 10:50:¶

@schabrolles
please explain all new variables in default.conf
that are meant to be set by the user in local.conf
(like your new PXE_CONFIG_GRUB_STYLE).

gdha commented at 2017-05-02 11:29:¶

@schabrolles Just out of curiosity - did you try it on x86 platforms as well?

schabrolles commented at 2017-05-02 11:38:¶

No, I don't have any x86 available ...

schlomo commented at 2017-05-02 11:44:¶

@schabrolles in a Virtual Machine on your desktop / laptop? Or is that also PPC64?

gdha commented at 2017-05-02 11:50:¶

@schabrolles Just comment the new variable in default.conf and the pull request is ready for being merged.

schabrolles commented at 2017-05-02 13:33:¶

@gdha I use a PXE_LINK_PREFIX variable to add "grub.cfg-" on configuration file generated only when we are using PXE_GRUB_STYLE.

But this variable PXE_LINK_PREFIX is local. May be I should name it in lower case ... What do you think ?

gdha commented at 2017-05-02 13:45:¶

@schabrolles when PXE_LINK_PREFIX is a local variable meant for PXE_GRUB_STYLE then I would rename it to PXE_GRUB_LINK_PREFIX to make it very clear and I would add it the default.conf file to have at least a brief description on what it is used for (over a couple of months I wouldn't know anymore)
@jsmeix @schlomo Do you agree?

jsmeix commented at 2017-05-02 14:06:¶

When PXE_LINK_PREFIX is a local variable
meant for PXE_GRUB_STYLE then I would
name it pxe_grub_link_prefix according to
https://github.com/rear/rear/wiki/Coding-Style

jsmeix commented at 2017-05-02 14:09:¶

The idea behind is that commands like

find . | xargs grep -i 'PXE_GRUB_'

could be used to 'grep' over the whole code and get a correct
overview what actually belongs to a particular "thingy".

schabrolles commented at 2017-05-02 14:22:¶

@gdha, I named it PXE_LINK_PREFIX because it can be used by any PXE type (legacy or grub).
For legacy PXE, PXE_LINK_PREFIX is empty, but it must be PXE_LINK_PREFIX="grub.cfg-" for grub style PXE.

@jsmeix, right now I think we can keep PXE_LINK_PREFIX local and not global... So I should rename it to pxe_link_prefix

gdha commented at 2017-05-02 14:32:¶

@schabrolles Are we all set to merge?

schabrolles commented at 2017-05-02 14:36:¶

@gdha From my point of view, yes .... But may be @jsmeix or @schlomo would like to add or change something ...

schabrolles commented at 2017-05-03 10:09:¶

@gdha ... Wait, I may be find a bug ... let me more time to investigate.

jsmeix commented at 2017-05-04 12:35:¶

@schabrolles
is it now o.k. to be merged from your point of view?

schabrolles commented at 2017-05-04 13:24:¶

Yep... look good, I made additional test by swapping different config ... it is now stable.

jsmeix commented at 2017-05-04 13:51:¶

@gdha
if you do not object, I will merge it soon...

jsmeix commented at 2017-05-04 14:29:¶

@schabrolles
again many thanks for your various contributions
that improve ReaR in particular on PPC architecture!

jsmeix commented at 2018-08-16 14:30:¶

In
https://github.com/rear/rear/issues/1899#issuecomment-413564261
I wonder why in conf/examples/RHEL7-PPC64LE-Mulitpath-PXE-GRUB.conf
there is (excerpt)

AUTOEXCLUDE_MULTIPATH=n
BOOT_OVER_SAN=y

but neither SAN nor multipath was mentioned here.
I.e. I wonder how PXE based on GRUB2 booting on PPC64/PPC64LE
is interconnected with BOOT_OVER_SAN and multipath.

jsmeix commented at 2018-08-17 09:49:¶

@schabrolles explained it in
https://github.com/rear/rear/issues/1899#issuecomment-413777499

[Export of Github issue for rear/rear.]

#1339 PR merged: Allow "grub PXE style" for non x86 platform.¶