Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <11af73e05bad75e4ef49067515e3214f6d944b3d.camel@gmail.com>
In-Reply-To: <11af73e05bad75e4ef49067515e3214f6d944b3d.camel@gmail.com>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Tue, 13 Dec 2022 09:51:33 +0100
Message-ID: <CACRpkdaXxPE3XhPnprhJ7GGjn9X_GMsCJ3mn26P90GcHzhsQDg@mail.gmail.com>
Subject: Re: [PATCH] of: fdt: Honor CONFIG_CMDLINE* even without /chosen node
To:     Alexander Sverdlin <alexander.sverdlin@gmail.com>
Cc:     devicetree@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@kernel.org>,
        Nikita Shubin <nikita.shubin@maquefel.me>,
        Hartley Sweeten <hsweeten@visionengravers.com>,
        Lukasz Majewski <lukma@denx.de>,
        Linus Walleij <linusw@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Dec 12, 2022 at 7:01 AM Alexander Sverdlin
<alexander.sverdlin@gmail.com> wrote:

> I do not read a strict requirement on /chosen node in either ePAPR or in
> Documentation/devicetree. Help text for CONFIG_CMDLINE and
> CONFIG_CMDLINE_EXTEND doesn't make their behavior explicitly dependent on
> the presence of /chosen or the presense of /chosen/bootargs.
>
> However the early check for /chosen and bailing out in
> early_init_dt_scan_chosen() skips CONFIG_CMDLINE handling which is not
> really related to /chosen node or the particular method of passing cmdline
> from bootloader.
>
> This leads to counterintuitive combinations (assuming
> CONFIG_CMDLINE_EXTEND=y):
>
> a) bootargs="foo", CONFIG_CMDLINE="bar" => cmdline=="foo bar"
> b) /chosen missing, CONFIG_CMDLINE="bar" => cmdline==""
> c) bootargs="", CONFIG_CMDLINE="bar" => cmdline==" bar"
>
> Move CONFIG_CMDLINE handling outside of early_init_dt_scan_chosen() so that
> cases b and c above result in the same cmdline.
>
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>

Excellent debugging Alexander!
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

I also think this should go to stable.

Yours,
Linus Walleij