posts/pcie-coral-tpu-ubuntu-server/

[giscus[bot]]

posts/pcie-coral-tpu-ubuntu-server/

example description

https://ignaspsk.dev/posts/pcie-coral-tpu-ubuntu-server/

[360elements360]

Thanks for this. As soon as I enter "sudo modprobe apex
" my whole computer freezes and I have to blacklist apex before it will boot again

[ignaspsk]

Hello and thanks for reading. Could you specify which OS version are you using? Also, what is the output of uname -r to confirm your kernel version? And does your system freeze when you run sudo modprobe gasket?
If it does, then it likely means that the issue is within gasket. Please include error messages, if any.

[360elements360]

Use Coral Edge TPU PCIe (1ac1:089a) on Ubuntu 24.04 while staying on 6.8.x kernels.
State: gasket builds/installs/loads. Device enumerates in lspci. System hard-freezes on modprobe apex (no /dev/apex_*), even with conservative PCIe flags.
Security: Secure Boot disabled; both gasket and apex modules are signed (MOK), so signing is not the blocker.
Environment

System: Dell Latitude E6440
CPU: Intel Core i7-4600M (Haswell) — family 6, stepping 3, microcode 0x28
Chipset/PCH: Intel QM87 / 8-Series C220
Host bridge: 8086:0c04
Root ports: 8086:8c10/8c18/8c1a/8c1c/8c1e
LPC/SMBus: 8086:8c4f, 8086:8c22
BIOS: Dell A16 (2016-12-22)
Kernels: Running 6.8.0-48-generic; also installed 6.8.0-85-generic
Cmdline (at capture):
... modprobe.blacklist=apex ro pci=nomsi pcie_aspm=off pci=noaer quiet splash vt.handoff=7

DKMS:
gasket/1.0, 6.8.0-48-generic: installed
gasket/1.0, 6.8.0-85-generic: installed

Modules (modinfo snippets):
gasket v1.1.4, vermagic 6.8.0-48-generic, signer pow Secure Boot Module Signature key
apex v1.2, vermagic 6.8.0-48-generic, signer pow Secure Boot Module Signature key
Secure Boot: mokutil --sb-state → disabled
Device presence (after moving card to another slot)
lspci -nn | grep -iE '1ac1|089a|coral|edge tpu'
04:00.0 System peripheral [0880]: Global Unichip Corp. Coral Edge TPU [1ac1:089a]
PCIe detail (sudo lspci -vvvxxx -s 04:00.0 — key points)
Link: Gen2 5.0 GT/s, x1 (LnkSta: Speed 5GT/s, Width x1)
ASPM: Disabled at link (L1.1/L1.2 capable but off)
Interrupts: Legacy INTx → IRQ 11; MSI-X (128) and MSI (1/32) present but disabled
Resources before bind: BAR0 16 KiB (64-bit, prefetchable), BAR2 1 MiB (64-bit, prefetchable) — Mem/BM disabled (expected pre-driver)
AER: Supported; header log present; no persistent fatal flags at dump time

Kernel modules (candidate): apex

What happened (chronology, condensed)
HWE 6.14.0-33 tried to build gasket via DKMS → failed (bad exit status: 2), breaking package config.
Purged HWE meta; stayed on 6.8.x.
Built gasket-dkms from source (debuild) and installed; DKMS built for 6.8.0-48 and 6.8.0-85.
Removed legacy blacklists; rebuilt initramfs.
Moved Coral to another PCIe slot → lspci sees 04:00.0 1ac1:089a.
modprobe gasket → loads (out-of-tree taint line appears; Secure Boot is off).
modprobe apex → hard-freeze (no log lines from apex before hang).
Tried kernel flags: pcie_aspm=off, pci=nomsi, pci=noaer (alone and combined) → still freezes.
Kept apex blacklisted to guarantee boot.

[ignaspsk]

Hi. Thanks for providing all the details. It seems you've run into a hardware incompatibility issue. This problem is really out of my expertise, but I've found that Coral PCIe (A+E key) TPU has non-standard electrical design where it shorts the 3.3V and 3.3VAUX power rails upon initialization. Your Dell Latitude E6440 might have a very strict power management system because of its business-class chipset and a 2016-era BIOS. When gasket driver tells the TPU to power on (triggered by modprobe apex) the motherboard's hardware protection circuitry probably detects this as a critical fault and immediately halts the system to prevent potential damage.

As a last-ditch effort, you could look for a "Legacy" or "Compatibility" power setting in the BIOS.

Unfortunately, this makes me think this combination is just incompatible. If you still want to use a Coral TPU, the USB version should work without any problems.
Sorry to bring you bad news.