From nobody Fri Sep 25 07:56:38 2026 Received: from mail.mdapi.ch (mail.mdapi.ch [31.3.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF3134AA57C; Tue, 15 Sep 2026 11:57:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=31.3.128.54 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473450; cv=none; b=XGFgmpoC35oOoFhGYnb70RmwJeS47i8dNqc4WdfxN8jm8xIa1M4b8S464FnKFzCpt60fAc1Knl1RIgUhROMJz3IHEnxeQGZnhKsTOm3sA09GE7f5+qbUiOAS2liTwqaY8HkJaKsJuoneATNkO+VXatv62e01j3J/wrviSJnMoks= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473450; c=relaxed/simple; bh=2ne5nnvy1AoxPawAFXFaeMiOw5oqhIP7Y/5CTDcjM1s=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Nw0IBaifN/jbTa278Ctmn0p/5cg6vNOpF5IZOVh32NtNMMng3HYhJ9RnKRsDm5XUJBdzFgwOGMRRVVYr7ltSXF74bOaKCmCvRXtwn/6tCyVDzeLyFhrwD9j5QE+ltZRXhA2eUP9qswElWsXJ0F6V9E9bEIGzvOaGfHuNJ05CarQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tillo.ch; spf=pass smtp.mailfrom=tillo.ch; dkim=pass (2048-bit key) header.d=tillo.ch header.i=@tillo.ch header.b=gLEEYnnm; arc=none smtp.client-ip=31.3.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tillo.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tillo.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tillo.ch header.i=@tillo.ch header.b="gLEEYnnm" From: Martino Dell'Ambrogio DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tillo.ch; s=mail202603; t=1789473442; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ix4zUneWseQ7vdoZIO9ZqqK5b1ofsYuNIFP6ohWZvWc=; b=gLEEYnnmonwrqeCPhxqBohgYdJfsQxDIMIemRm5bC7lnm2XjBcNIgyd2xT8FBA+2VWG/oC GK1P6B/d4ZikTPOjmsiElND5nzCDug6W33eAUAe+R1A0pIV3gpwkduAvJ625246EfCILHT fzVhGwNQBOTLexuRjqloMvAXYSE5HyofvAI4w/th18Y0BwEFULwb2gP8vTmoFqZIl7ULLN 0P2TSKyhzzjE3DSHDgzJjynbDogW/c8WdrMzWfiF713ethU4b5f8t36AGWlv85QcsY4WqS 7VftbrKSwK4JNTmFu18+dFvHzwoSQsFPTHH05okKTPglZzznFR2Y1j27GENClA== To: Matthias Brugger , AngeloGioacchino Del Regno Cc: linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kees@kernel.org, tony.luck@intel.com, gpiccoli@igalia.com Subject: [PATCH v4] arm64: dts: mediatek: mt7988a-bananapi-bpi-r4: add ramoops region Date: Tue, 15 Sep 2026 13:57:22 +0200 Message-ID: <20260915135722.566918-1-tillo@tillo.ch> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Reserve 1 MiB of RAM just below the ARM Trusted Firmware secmon region (0x42f00000-0x43000000) for persistent kernel log storage via pstore/ramoop= s, allowing post-panic console output and oops dumps to be recovered after a reboot. Without it, kernel crash logs on this board are lost when the SoC warm-resets and the on-chip console buffer is reinitialised. With record-size=3D128 KiB, console-size=3D256 KiB, ftrace-size=3D64 KiB and pmsg-size=3D64 KiB, ramoops_probe() carves the post-console remainder (640 KiB) into five 128 KiB kmsg records, with the requested ecc-size=3D16 reserving a small Reed-Solomon parity block from each zone's own allocation (per persistent_ram_new()). The ECC lets pstore recover dumps even when the panic path truncates writes mid-record. The no-map property is required so the reserved region is kept out of the kernel linear map. ramoops remaps the carve-out write-combine via ioremap_wc(); on arm64, leaving the same physical RAM mapped cacheable in the linear map at the same time is an attribute-mismatch and risks losing panic data to dirty cache evictions from the linear alias. The carve-out sits immediately below the ATF region already declared at 0x43000000 in mt7988a.dtsi, so no other reserved-memory child is moved or resized. BPI-R4 ships with at least 4 GiB of DRAM starting at 0x40000000, so the region is well within installed memory on every variant. For the carve-out to actually preserve content across a reset, the boot loader must also avoid touching this region on warm reset; on standard BPI-R4 boards with the stock OpenWrt U-Boot fork this already holds. Signed-off-by: Martino Dell'Ambrogio --- Changes in v4: - Use a plain reserved-memory node inside the root node instead of the &{/reserved-memory} path reference, as AngeloGioacchino pointed out. dtc merges it with the node from mt7988a.dtsi, so the resulting DTB is identical; this is a syntax change only. Same change made to the BPI-R3 patch. No rush on my account for the earlier silence - the v2 postings were cross-threaded into each other's v1, so they were easy to miss. For what it is worth, this layout is in use on a BPI-R4 here: the kernel brings it up as OF: reserved mem: 0x42f00000..0x42ffffff (1024 KiB) nomap non-reusable pstore: Registered ramoops as persistent store backend ramoops: using 0x100000@0x42f00000, ecc: 16 (that build carries the same node via the path-reference form, so the DTB is the one this patch produces). I have not yet confirmed a panic dump survives end to end on it. v3: https://lore.kernel.org/all/20260915064254.1594808-1-tillo@tillo.ch/ v2: https://lore.kernel.org/all/20260528123645.2650085-1-tillo@tillo.ch/ v1: https://lore.kernel.org/all/20260528092807.1936177-1-tillo@tillo.ch/ .../boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi b/ar= ch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi index 0ff69da..75f5940 100644 --- a/arch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi +++ b/arch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi @@ -66,6 +66,19 @@ regulator-always-on; }; =20 + reserved-memory { + ramoops@42f00000 { + compatible =3D "ramoops"; + reg =3D <0 0x42f00000 0 0x100000>; + no-map; + record-size =3D <0x20000>; + console-size =3D <0x40000>; + ftrace-size =3D <0x10000>; + pmsg-size =3D <0x10000>; + ecc-size =3D <16>; + }; + }; + /* SFP1 cage (WAN) */ sfp1: sfp1 { compatible =3D "sff,sfp"; --=20 2.47.3