Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 20 Mar 2024 13:05:57 -0700 | Subject | Re: [PATCH v4 1/2] of: create of_root if no dtb provided | From | Guenter Roeck <> |
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On 3/20/24 12:14, Rob Herring wrote: > On Mon, Mar 18, 2024 at 4:31 PM Guenter Roeck <linux@roeck-us.net> wrote: >> >> On 3/18/24 12:26, Rob Herring wrote: >>> +Stephen >>> >>> On Mon, Mar 18, 2024 at 12:09 PM Guenter Roeck <linux@roeck-us.net> 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@gmail.com> >>>> >>>> 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. >>> >> >> For nios2, in early_init_devtree(): >> >> void __init early_init_devtree(void *params) >> { >> __be32 *dtb = (u32 *)__dtb_start; >> ... >> if (be32_to_cpu((__be32) *dtb) == OF_DT_HEADER) >> params = (void *)__dtb_start; >> >> That worked fine until this patch. Starting with this patch, __dtb_start >> always points to a valid empty devicetree blob, which overrides the >> devicetree blob passed to early_init_devtree(). This causes the problem. > > With an external DTB, it doesn't boot with or without this patch. It > just dies in different spots. Before it just skipped any memory
No, that is incorrect. Up to this patch it booted just fine with an external dtb using the "-initrd" command line argument, and I explained to you above why this is the case.
I guess you are saying I should stop boot testing nios2. I'll do just that. Saves me resources and avoids discussions like this.
Guenter
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