On Tue, Jan 22, 2019 at 07:34:39PM +0000, Tristan Bastian wrote: > > > > Thierry Reding – Tue, 22. January 2019 17:13 > > 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: > > 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 > > Hi Thierry, > > I'm using coreboot. > But what I can also tell is, that when you use U-Boot chainloaded to coreboot, LPAE is also not working with older kernel revisions like 4.18. > I only found a single memory entry in /sys/firmware/devicetree/ "memory@80000000"... > > BTW: @Thierry, I'm reverting this patch: https://patchwork.kernel.org/patch/9516105/ because otherwise I'm getting a blank screen on bootup. Is there any fix for that going upstream? Yes, there was some work to get that fixed, but it keeps getting stuck. I'll resume the old threads to see if we can gain some traction. Can I add you on Cc for testing any patch related to that? Thierry
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