Hi Andre, On 23-08-24 14:50, Andre Przywara wrote: > On Wed, 23 Aug 2023 21:36:51 +0200 > Jernej Škrabec <jernej.skrabec@xxxxxxxxx> wrote: > > > Hi Andrey, > > > send new revision as standalone e-mail, not as reply to old discussion. > > > > Dne torek, 22. avgust 2023 ob 11:23:58 CEST je Andrey Skvortsov napisal(a): > > > This patch reserves some memory in the DTS and sets up a > > > pstore device tree node to enable pstore support. > > > > > > In general any DRAM address, that isn't overwritten during a boot is > > > suitable for pstore. > > > > > > Range from 0x40000000 - 0x50000000 is heavily used by u-boot for > > > internal use and to load kernel, fdt, fdto, scripts, pxefile and ramdisk > > > later in the boot process. Ramdisk start address is 0x4FF00000, > > > initramfs for kernel with some hacking features and debug info enabled > > > can take more than 100Mb and final address will be around 0x58000000. > > > Address 0x61000000 will most likely not overlap with that. > > > > There are other bootloaders as U-Boot, especially on PinePhone. Are you sure > > it works there too? What about U-Boot configuration, will those addresses still > > be used if configuration is changed? > > Also going along with what Pavel said (that's it more a policy > decision, not a device property), I feel like this node should be added > by the bootloader then. And indeed U-Boot has support for that already. > From skimming over the code in cmd/pstore.c: if you enable > CONFIG_CMD_PSTORE and set CONFIG_CMD_PSTORE_MEM_ADDR to your chosen > address, then the U-Boot code will insert a reserved memory node on the > fly. Would that solve your problem? > I've tried pstore command in u-boot in the past to make sure it's working there as well. I didn't know, that it adds reserved-memory node as well. Thanks, Andre. That is very helpful. I've tried it again without patching a kernel as you suggested. Unfortunately it's not working on A64. If there is no reserved-memory defined, u-boot adds a new one with following properties: reserved-memory { #address-cells = <2>; #size-cells = <2>; ranges; } But with these default address-cells and size-cells values, pstore isn't working on A64. Root node for A64 defines 'address-cells' and 'size-cells' as 1. dtc complains if reserved-memory has different address-cells and size-cells. ``` Warning (ranges_format): /reserved-memory:ranges: empty "ranges" property but its #address-cells (2) differs from / (1) ``` If empty reserved-memory is added to arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi in the kernel, then u-boot adds working pstore subnode. ``` reserved-memory { #address-cells = <1>; #size-cells = <1>; ranges; /* bootloader will add new entries here * for example, for pstore. */ }; ``` It looks like a bug in u-boot for me. IMHO, it should look at #address-cells/#size-cells of the root-node for default values. I have tried that and this way pstore is working without any changes to the kernel dts. What do you think? Should I submit fix to u-boot instead? -- Best regards, Andrey Skvortsov