Received-SPF: pass (google.com: domain of linux-kernel+bounces-106567-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Precedence: bulk
MIME-Version: 1.0
References: <20230317053415.2254616-1-frowand.list@gmail.com>
 <20230317053415.2254616-2-frowand.list@gmail.com> <886049ed-4f5f-4e17-86f4-1245024ade3a@roeck-us.net>
In-Reply-To: <886049ed-4f5f-4e17-86f4-1245024ade3a@roeck-us.net>
From: Rob Herring <robh+dt@kernel.org>
Date: Mon, 18 Mar 2024 14:26:00 -0500
Message-ID: <CAL_JsqKsF53v7d7uZ3XT4kPFy-2FBWHfvKNSFdTx2oZhmSZkDA@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] of: create of_root if no dtb provided
To: Guenter Roeck <linux@roeck-us.net>, Stephen Boyd <sboyd@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>, =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= <clement.leger@bootlin.com>, 
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Lizhi Hou <lizhi.hou@xilinx.com>, Allan Nielsen <allan.nielsen@microchip.com>, 
	Horatiu Vultur <horatiu.vultur@microchip.com>, 
	Steen Hegelund <steen.hegelund@microchip.com>, 
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

+Stephen

On Mon, Mar 18, 2024 at 12:09=E2=80=AFPM 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 al=
locate 72 bytes align=3D0x40
> ---[ end Kernel panic - not syncing: early_init_dt_alloc_memory_arch: Fai=
led to allocate 72 bytes align=3D0x40 ]---

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