On 09/21/2017 07:02 PM, Lennart Sorensen wrote: > On Thu, Sep 21, 2017 at 06:26:10PM +0200, John Paul Adrian Glaubitz wrote: >> Ok, good to know. What about GPT partition tables? On ppc64el, i.e. POWER8 >> and newer, the default labels are all GPT. Any idea which is the earliest >> POWER5+ machine which supports GPT or should we just assume MS-DOS >> partition tabels for all POWER machines? > > I unfortunately never tried GPT on any IBM power machines and I no longer > have access to them.
I have one POWER7 machine that has been provided to me by IBM for testing purposes and to host one of our buildds. I have performed a test installation of openSUSE Tumbleweed on it. Here's the partitioning scheme that is being used: (parted) p Model: Virtio Block Device (virtblk) Disk /dev/vda: 42.9GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 2097kB 1049kB primary boot, prep, type=41 2 2097kB 2163MB 2161MB primary linux-swap(v1) type=82 3 2163MB 18.9GB 16.7GB primary btrfs type=83 4 18.9GB 42.9GB 24.0GB primary xfs type=83 (parted) Interestingly, /boot is part of the btrfs filesystem: linux-mfl2:~ # mount | grep boot /dev/vda3 on /boot/grub2/powerpc-ieee1275 type btrfs (rw,relatime,space_cache,subvolid=261,subvol=/@/boot/grub2/powerpc-ieee1275) linux-mfl2:~ # > I found this: > > http://download.boulder.ibm.com/ibmdl/pub/software/server/firmware/AH-Firmware-Hist.html > > So it claims that on power7 the firmware upgrade in 2013 added support > for booting from a GPT disk. So to me that means a lot of power7 systems > out there won't be able to (since not everyone has updated the firmware). > It doesn't say what you have to create as a boot partition when using > GPT though, so no idea how one would use it. It might support FAT32 > filesystem and accessing the grub file the way UEFI systems do, and > similar to what I think PowerMac machines do. > > I can't find anything to suggest any power6 or power5 system ever had > an update to allow it. Ok, so I guess we can basically rule out GPT for the default label even on POWER systems. I would therefore then vote for using MS-DOS partition tables on POWER systems, i.e. what is already used now. > I would expect all power8 machines had GPT support from the start, > and hence defaulting to that makes sense. I agree. >>> The grub modules stay in whatever /boot is on, and the grub image >>> generated contains enough of grub to read filesystems and is loaded >>> by the firmware from the prep boot partition (it litterally reads that >>> partition into ram as raw data, and executes it). >> >> Interesting. Do you know whether the mechanism is the same? My worries >> are that users on older PowerPC hardware, especially Apple Macintosh >> would have to go through extra lengths to get this working. > > On a powermac is is certainly different. You would have an apple > partition table instead, along with whatever else a mac requires boot wise > (which I don't know off hand). So, MS-DOS partition tables will not work at all on a Mac, correct? Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - glaub...@debian.org `. `' Freie Universitaet Berlin - glaub...@physik.fu-berlin.de `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
