On Tue, Jan 22, 2019 at 03:23:51PM +0000, Tristan Bastian wrote: > Hello, > > since mainline kernel 4.19 LPAE is no longer working for me and some others on tegra124-nyan-big. > Is this a known problem with a fix already available? > > The defconfig to compile the kernel can be found here: https://github.com/reey/PKGBUILDs/blob/master/core/linux-nyan/nyan-big_defconfig > Basically we are only getting 2 GB instead of 4 GB of memory. > Kernel 4.18 still gives us 4 GB. > Both kernels are configured with CONFIG_ARM_LPAE=y. > All newer kernel versions also have this bug.. Looking at the git log, I can only find one possibly suspicious change: commit 482997699ef038af7553399d49b7ba74c3301424 Author: Krzysztof Kozlowski <krzk@xxxxxxxxxx> Date: Mon Jul 9 18:05:17 2018 +0200 ARM: tegra: Fix unit_address_vs_reg DTC warnings for /memory Add a generic /memory node in each Tegra DTSI (with empty reg property, to be overidden by each DTS) and set proper unit address for /memory nodes to fix the DTC warnings: arch/arm/boot/dts/tegra20-harmony.dtb: Warning (unit_address_vs_reg): /memory: node has a reg or ranges property, but no unit name The DTB after the change is the same as before except adding unit-address to /memory node. Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx> Reviewed-by: Stefan Agner <stefan@xxxxxxxx> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> I suppose this could result in the bootloader failing to find the memory node when trying to patch up the memory banks. It looks like U-Boot handles this properly by ignoring the unit-address when looking up nodes by name (without unit-address), but I suspect that coreboot may not be doing this. I'm assuming that coreboot is what you're using as bootloader? If coreboot behaves similarly to U-Boot, it'll create a new node if it can't find a matching one, so you may be able to inspect the device tree that was passed to the kernel (/sys/firmware/fdt should have the binary and /sys/firmware/devicetree should have a directory tree representation of the device tree). Thierry
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