Hi Mathieu, > TL;DR: anyone against adding --no-nvram to grub-install calls for > grub-ieee1275, in postinst for ppc64el?
No, nothing against that, on the contrary. Also after querying some other people more knowledgeable , especially Paulo Smorigo (grub contributor), he told : "I agree with adding no-nvram of postinst for ppc64el. My option is that the installer should not touch boot-device parameter at all and this is something that the user or a management system should do. GRUB overwrites all values in boot-device (previous boot-devices are removed not appended). I had some issues in the past where a system had a network installation and after it finished the system starts to boot locally and this is not what the management system wanted." > I've been looking at issues with some scripted (not d-i and not > preseeded...) installs running grub-install on ppc64el, leading to the > nvram variable "boot-device" being mangled by grub-install when it is > run with just: > > grub-install --target=powerpc-ieee1275 > > The result would generally be of the format: > > /path/to/device:2,\boot\grub\powerpc-ieee1275\core.elf > > This is wrong on PowerVM systems. They don't go into the partition to > read ext2 and read the bootloader, but instead expect things to be > written to a PReP partition, and for that partition to be pointed to by > disk path only (the above path, up to the colon). > > Unfortunately, I don't know enough about all of the ppc64el systems to > know if there is some type of firmware that accepts this value as valid > to point to the bootloader. I did a bit of investigation. Especially, for my information, I read some docs and share bits of it here. According to the IEEE1275 Standard for Boot, that specification is valid. The part "2,\boot\grub\powerpc-ieee1275\core.elf" is called the device-arguments and "is interpreted by the driver and typically represents additional device information, such as partition name or protocol. The device arguments field and its preceding “ : ” may be omitted when specifying a node name, as it does not serve to identify the device node ; instead, it is passed to that node’s open method if that driver is opened." For ppc64el, there is 3 cases : - PowerVM : boot-device is used by the OF ; GPT is supported but ext2 is not supported (FAT would work) and that's where we fail to load. An OF developer confirmed missing extX support. - PowerNV : petitboot reads directly the partitions and auto-detects grub's installtion : not used here. - qemu VM : boot-device is used by SLOF, and SLOF supports ext2 but not ext3/4 yet. Also, on guests, on Debian/Ubuntu, boot-device is never updated because of a patch of Colin Watson ; maybe that should be extended to chrp_ibm <-> PowerVM. So the value you describe is valid, but currently the firmwares don't support some filesystems that Debian/Ubuntu use. Note : boot-device can also specify multiple possible values, I tried and it works if we add a 2nd value as fallback with only the disk node name value. > Furthermore, grub-install is called as above for every run of the > grub-ieee1275 postinst in the configure case, so presumably for every > upgrade of grub. This would mean a mangled nvram as soon as you upgrade > grub, even if you fixed it manually already. > > Even if it was set to the correct value, it seems unnecessary to modify > nvram only to re-write the same config variable again with the same value. > > I've discussed this with infinity for Ubuntu and we've come to the > conclusion that grub should not change nvram, except in the installation > case, where it's already being handled by grub-installer (which runs > grub-install on its own, without --no-nvram, and that is fine). Also according to Paulo : "Now about pointing to a core.elf directly (like, grub-install without a device), my option is that it's prone to error due to OpenFirmware (and SLOF) limitations. [...] it's not the safer path and that's why PReP partition exists (grub-install with a device)." So to summarize, the advised behaviour at the moment, should be to make use of the PReP partition and not change boot-device. F.
