AmpereOne M / A4 on Oracle Cloud: MTE not exposed, even on bare metal (ID_AA64PFR1_EL1.MTE = 0)

Q&A
1

Posting a measurement in case it’s useful to others, and to ask whether it’s expected.

I wanted an AmpereOne system with Arm MTE for memory-safety research on language runtimes. OCI’s A4 shapes use AmpereOne M (A06-36M), which should be Ampere-1a and therefore MTE-capable. MTE is not exposed, and it isn’t the hypervisor.

Bare metal — BM.Standard.A4.48, Oracle Linux 10.1 aarch64, kernel 6.12.0 UEK:

systemd-detect-virt        : none          (no hypervisor)
CPU implementer            : 0xc0
CPU part                   : 0xac4         (Ampere-1a)
Model name                 : Ampere-1a
Thread(s) per core         : 1
Cores                      : 96,  754 GB RAM
CONFIG_ARM64_MTE           : y
cmdline                    : no 'nomte'
ID_AA64PFR1_EL1            : 0x0000000000000021
  MTE field (bits 11:8)    : 0
AT_HWCAP2                  : 0xb6181   -> HWCAP2_MTE NOT set
BIOS vendor/version/date   : Oracle / 94002900 / 03/23/2026
System                     : ORACLE SERVER A4-2c

A VM.Standard.A4.Ax.Flex instance shows the same, so this is consistent across both tiers.

Since systemd-detect-virt reports none on the bare-metal node, KVM passthrough is ruled out, and the ID register itself reports no MTE. That points at the UEFI NVPARAM being unset in the platform firmware, consistent with the documented requirement to enable MTE via NVPARAM (nvparam -s NVPDBOOT -i 56 -w 0x1 on a Supermicro ARS-211M-NR, per a writeup I found). There’s no nvparam tool or UEFI shell reachable from the OS on OCI, so it can’t be set guest-side.

Questions:

  1. Is MTE expected to be disabled by default in OEM/cloud firmware builds, or is this specific to Oracle’s image?
  2. Is there any path to it being enabled on OCI A4 — is that an Oracle product decision, or something Ampere works with partners on?
  3. Is there a currently-available AmpereOne platform, rental or purchase, that ships with MTE enabled, or where the buyer can set the NVPARAM? Most bare-metal AmpereOne offerings I can find are X-series parts, and the affordable dev kits are all Altra, which lacks MTE entirely.

Happy to re-run anything on a fresh instance — it costs a couple of dollars and I have the process scripted.

(Related prior work: Optimized Memory Tagging on AmpereOne Processors, arXiv 2511.17773.)