From 3a766bf2a39ea0e69e1030db719c4136f20bb608 Mon Sep 17 00:00:00 2001 From: Martino Dell'Ambrogio Date: Tue, 15 Sep 2026 13:57:22 +0200 Subject: arm64: dts: mediatek: mt7988a-bananapi-bpi-r4: add ramoops region Reserve 1 MiB of RAM just below the ARM Trusted Firmware secmon region (0x42f00000-0x43000000) for persistent kernel log storage via pstore/ramoops, 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=128 KiB, console-size=256 KiB, ftrace-size=64 KiB and pmsg-size=64 KiB, ramoops_probe() carves the post-console remainder (640 KiB) into five 128 KiB kmsg records, with the requested ecc-size=16 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 Signed-off-by: AngeloGioacchino Del Regno --- arch/arm64/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/arch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4.dtsi index 0ff69dae45d3..75f59407794f 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; }; + reserved-memory { + ramoops@42f00000 { + compatible = "ramoops"; + reg = <0 0x42f00000 0 0x100000>; + no-map; + record-size = <0x20000>; + console-size = <0x40000>; + ftrace-size = <0x10000>; + pmsg-size = <0x10000>; + ecc-size = <16>; + }; + }; + /* SFP1 cage (WAN) */ sfp1: sfp1 { compatible = "sff,sfp"; -- cgit v1.2.3