create_disk: move /boot to partition 3; move BIOS-BOOT to 1 and always create it #1820
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Skipping CI for Draft Pull Request. |
Just to make sure I follow, can you expand on this a little more? Is it that by having it be the first partition, it makes it less likely that it would be moved around and so we avoid having to update the MBR? |
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We can't update the boot sector unless we want to rerun grub-install from the initrd or hand-hack the bits, neither of which is appealing. So a recreated BIOS-BOOT partition needs to remain at the same offset as the original. Putting it at the beginning of the disk is relatively natural. Putting it at 512 MiB, as we do now, means we'd need to hardcode that constant into the FCCT desugaring code that lays out the new partitions. |
bgilbert
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bgilbert
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Ready for review. |
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One minor comment, but LGTM overall!
I think it's worth raising visibility on this somehow because this will break anyone/anything which currently uses e.g. /dev/sda1 for the boot partition instead of by-label (I'm definitely guilty of that myself). WDYT about a ticket in the tracker which says that we want to move the /boot partition and linking to this PR (or better, having this PR close it)?
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/test sanity |
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Updated! |
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Awesome, thanks for opening the tracker issue! /lgtm |
The offset of the BIOS boot partition gets encoded into the boot sector, and that offset is currently 512 MiB, which is awkward if we're going to support rearranging boot-related partitions. Move the BIOS boot partition to partition 1 at the beginning of the disk, and move /boot to partition 3 on all platforms (including ppc64le, where it was overridden to partition 2).
Reduce the number of partition layouts we create, in order to simplify the maintenance of Ignition configs that affect the default partition table. Continue not installing BIOS GRUB in the 4Kn image, since it'll never be invoked.
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Rebased. |
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/lgtm |
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The boot filesystem was moved to partition 3 recently. Let's update the code to be a little more dynamic about finding the boot paritition so we can be forward and backward compatible. For more context see: - coreos/fedora-coreos-tracker#669 - coreos/coreos-assembler#1820
The boot filesystem was moved to partition 3 recently. Let's update the code to be a little more dynamic about finding the boot paritition so we can be forward and backward compatible. For more context see: - coreos/fedora-coreos-tracker#669 - coreos/coreos-assembler#1820
The boot filesystem was moved to partition 3 recently. Let's update the code to be a little more dynamic about finding the boot paritition so we can be forward and backward compatible. For more context see: - coreos/fedora-coreos-tracker#669 - coreos/coreos-assembler#1820
The offset of the BIOS boot partition gets encoded into the boot sector, and that offset is currently 512 MiB, which is awkward if we're going to support rearranging boot-related partitions. Move the BIOS boot partition to partition 1 at the beginning of the disk, and move
/bootto partition 3 on all platforms (includingppc64le, where it was overridden to partition 2).In addition, create an unused BIOS boot partition on 4Kn disks. This reduces the number of distinct partition layouts we need to support.
For coreos/fedora-coreos-config#718, but shouldn't be required by it. Closes coreos/fedora-coreos-tracker#669.