+Stephen On Mon, Mar 18, 2024 at 12:09 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > Hi, > > On Fri, Mar 17, 2023 at 12:34:14AM -0500, Frank Rowand wrote: > > When enabling CONFIG_OF on a platform where of_root is not populated by > > firmware, we end up without a root node. In order to apply overlays and > > create subnodes of the root node, we need one. Create this root node > > by unflattening an empty builtin dtb. > > > > If firmware provides a flattened device tree (FDT) then the FDT is > > unflattened via setup_arch(). Otherwise setup_of(), which is called > > immediately after setup_arch(), will create the default root node > > if it does not exist. > > > > Signed-off-by: Frank Rowand <frowand.list@xxxxxxxxx> > > This patch results in a crash on nios2. This patch was never applied. I assume you meant a later version of it that did get applied. > > Building nios2:10m50-ghrd:10m50_defconfig:10m50_devboard.dts ... running ...R failed (crashed) Booting with DT? > ------------ > qemu log: > earlycon: uart8250 at MMIO32 0x18001600 (options '') > printk: legacy bootconsole [uart8250] enabled > Linux version 6.8.0-11409-gf6cef5f8c37f (groeck@desktop) (nios2-linux-gcc (GCC) 11.4.0, GNU ld (GNU Binutils) 2.40) #1 Sun Mar 17 23:38:59 PDT 2024 > Kernel panic - not syncing: early_init_dt_alloc_memory_arch: Failed to allocate 72 bytes align=0x40 > ---[ end Kernel panic - not syncing: early_init_dt_alloc_memory_arch: Failed to allocate 72 bytes align=0x40 ]--- nios2 looks utterly broken to me. This change should be a nop unless initial_boot_params is NULL. It looks like it is possible for r6 (dtb address) to be 0 depending on kconfig options, but that would have skipped copying and unflattening which would then panic in setup_cpuinfo(). If initial_boot_params is not NULL, then the same early_init_dt_alloc_memory_arch() calls should fail when copying the DT. So I don't see how nios2 booting with DT ever worked. Rob
