PureOS stops booting with firmware error

[MrChromebox]

@rrog

[    0.334631] DMAR: DRHD: handling fault status reg 3
[    0.334647] DMAR: [DMA Read] Request device [00:02.0] fault addr 7c412000 [fault reason 06] PTE Read access is not set
[    0.335724] DMAR: DRHD: handling fault status reg 3
[    0.335745] DMAR: [DMA Read] Request device [00:02.0] fault addr 7c432000 [fault reason 07] Next page table ptr is invalid
[    0.336810] DMAR: DRHD: handling fault status reg 3
[    0.336829] DMAR: [DMA Read] Request device [00:02.0] fault addr 7c4a1000 [fault reason 07] Next page table ptr is invalid
[    0.336838] DMAR: DRHD: handling fault status reg 3

these are IOMMU related, but not fatal – are you running the latest Purism firmware? (4.12-Purism-4)

[ 1.401717] i915 0000:00:02.0: firmware: failed to load i915/kbl_dmc_ver1_04.bin (-2)
[ 1.401720] firmware_class: See Firmware - Debian Wiki for information about missing firmware

these are spurious, and due to the fact that PureOS does not include (nor load) load driver blobs.

Neither of these errors would explain a failure to boot. So question time:

• what did you do or change recently?
• any OS updates installed?
• running latest coreboot firmware?