[Bug 2169339] Re: [iMac18,2] BCM43602 Wi-Fi (brcmfmac) cannot associate on 7.3 kernels: DMAR DMA Read faults, firmware hangs; works with intel_iommu=off

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2169339 Title: [iMac18,2] BCM43602 Wi-Fi (brcmfmac) cannot associate on 7.3 kernels: DMAR DMA Read faults, firmware hangs; works with intel_iommu=off Status in linux package in Ubuntu: New Bug description: On an iMac18,2 (2017) with a Broadcom BCM43602 [14e4:43ba] (subsystem Apple [106b:016e]), Wi-Fi no longer connects since the installed system moved to the 7.3 kernel. Booting with intel_iommu=off makes it work again. Wi-Fi worked in the Ubuntu 26.10 live session used to install the machine (kernel 7.2.0-5, image of 2026-09-15). The installer then upgraded to linux 7.3.0-5 and removed 7.2.0-5, and Wi-Fi has failed on every boot since (7.3.0-5, 7.3.0-6 and 7.3.0-8, 13 boots in total). I have no logs from the 7.2 live session, so I cannot tell whether the IOMMU was enabled there. What happens on a default boot: 1. brcmfmac loads, firmware starts, wlp3s0 appears, the initial scan works (the access point is listed with a strong signal). 2. As soon as association starts, the IOMMU reports two faults for the Wi-Fi device: DMAR: DRHD: handling fault status reg 2 DMAR: [DMA Read NO_PASID] Request device [0000:03:00.0] fault addr 0xfffa3000 [fault reason 0x06] PTE Read access is not set DMAR: [DMA Read NO_PASID] Request device [0000:03:00.0] fault addr 0xfffa5000 [fault reason 0x06] PTE Read access is not set (the addresses vary between boots, e.g. 0xfff64000 / 0xfff65000) 3. The firmware stops answering: ieee80211 phy0: brcmf_msgbuf_query_dcmd: Timeout on response for query command ieee80211 phy0: brcmf_get_assoc_ies: could not get assoc info (-5) 4. After a few minutes the control ring fills up: ieee80211 phy0: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring ieee80211 phy0: brcmf_run_escan: error (-12) 5. NetworkManager: "association took too long, failing activation", reason 'ssid-not-found', retried forever. WORKAROUND Adding intel_iommu=off to the kernel command line. With it, on the same kernel (7.3.0-8-generic): no DMAR fault, no firmware timeout, association succeeds within seconds and traffic flows (IPv4 and IPv6). The usual BCM43602 workarounds were already in place and did not help: options brcmfmac feature_disable=0x82000 roamoff=1 options cfg80211 ieee80211_regdom=FR SYSTEM Release: Ubuntu 26.10 "Stonking Stingray" (development branch) Kernel: 7.3.0-8-generic (7.3.0-8.8, based on 7.3.0-rc5); also 7.3.0-5.5 and 7.3.0-6.6 Machine: Apple iMac18,2 Wi-Fi: Broadcom BCM43602 802.11ac [14e4:43ba] rev 01, subsystem Apple [106b:016e] Driver: brcmfmac (in-tree), firmware brcm/brcmfmac43602-pcie Firmware: BCM43602/1 wl0: Nov 10 2015 06:38:10 version 7.35.177.61 (r598657) FWID 01-ea662a8c linux-firmware: 20260915.git1522c78a wpasupplicant: 2:2.11-2ubuntu2 Kernel config: CONFIG_INTEL_IOMMU_DEFAULT_ON=y, CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON=y, IOMMU default domain type "Translated", lazy TLB invalidation Secure Boot: not supported on this machine Note: a custom NVRAM file /lib/firmware/brcm/brcmfmac43602-pcie.txt was added on 2026-09-20 while trying to fix this. The failure already occurred on the boots before that file existed. Note: the logs attached automatically by apport come from a boot with intel_iommu=off (working). Kernel log excerpts from a failing boot (default command line) are attached separately as dmesg-failing- boot.txt. ProblemType: Bug DistroRelease: Ubuntu 26.10 Package: linux-image-7.3.0-8-generic 7.3.0-8.8 ProcVersionSignature: Ubuntu 7.3.0-8.8-generic 7.3.0-rc5 Uname: Linux 7.3.0-8-generic x86_64 ApportVersion: 2.36.0-0ubuntu1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: parents 18057 F.... wireplumber /dev/snd/controlC1: parents 18057 F.... wireplumber /dev/snd/seq: parents 18053 F.... pipewire CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Fri Oct 2 22:10:14 2026 InstallationDate: Installed on 2026-09-19 (13 days ago) InstallationMedia: Ubuntu 26.10 "Stonking Stingray" - Daily amd64 (20260915) MachineType: Apple Inc. iMac18,2 ProcEnviron: LANG=fr_FR.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.3.0-8-generic root=UUID=449c41b8-da4d-4c34-ad74-1f7a5e150bb0 ro quiet splash intel_iommu=off crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/11/2022 dmi.bios.release: 0.1 dmi.bios.vendor: Apple Inc. dmi.bios.version: 451.140.1.0.0 dmi.board.name: Mac-77F17D7DA9285301 dmi.board.vendor: Apple Inc. dmi.board.version: iMac18,2 dmi.chassis.type: 9 dmi.chassis.vendor: Apple Inc. dmi.chassis.version: Mac-77F17D7DA9285301 dmi.modalias: dmi:bvnAppleInc.:bvr451.140.1.0.0:bd04/11/2022:br0.1:svnAppleInc.:pniMac18,2:pvr1.0:rvnAppleInc.:rnMac-77F17D7DA9285301:rvriMac18,2:cvnAppleInc.:ct9:cvrMac-77F17D7DA9285301:sku:pfaiMac: dmi.product.family: iMac dmi.product.name: iMac18,2 dmi.product.version: 1.0 dmi.sys.vendor: Apple Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2169339/+subscriptions