linux-kernel - Re: [PATCH] of: print warning when cmdline overflows from bootargs

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Message-ID: <bc7281f5-bce6-407b-96e1-18293f373921@linux.dev>
Date: Tue, 2 Dec 2025 10:17:03 +0800
From: "enlin.mu" <enlin.mu@...ux.dev>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: robh@...nel.org, saravanak@...gle.com, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, enlin.mu@...soc.com
Subject: Re: [PATCH] of: print warning when cmdline overflows from bootargs



On 2025/11/6 16:55, Krzysztof Kozlowski wrote:
> On Wed, Nov 05, 2025 at 04:27:17PM +0800, Enlin Mu wrote:
>> From: Enlin Mu <enlin.mu@...oc.com>
>>
>> add debug info. sometimes cmdline in dts is too long,
> 
> I don't see debug info here.
> 
> Please use full sentences, starting with capital letter and ending with
> full stop.
> 
> Please wrap commit message according to Linux coding style / submission
> process (neither too early nor over the limit):
> https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597
> 
> 
>> developers are not aware of the length limit of the
>> cmdline, resulting in some misjudgments.
>>
>> Signed-off-by: Enlin Mu <enlin.mu@...oc.com>
>> ---
>>   drivers/of/fdt.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index 0edd639898a6..077799b2f565 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -1085,6 +1085,8 @@ int __init early_init_dt_scan_chosen(char *cmdline)
>>   	p = of_get_flat_dt_prop(node, "bootargs", &l);
>>   	if (p != NULL && l > 0)
>>   		strscpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
>> +	if (l > COMMAND_LINE_SIZE)
>> +		pr_warn("cmdline overflows from bootargs\n");
> 
> Why only OF early should have this warning and cmdline passed via ATAGS
> or in ACPI system should not?
I have a Raspberry Pi 5, so I can test my patch. But for chips with 
other architectures, I don't have the equipment and I am not very
familiar with them. If you are familiar with other architectures,
I hope you can help impore the patch or independently complete this
idea.

Thanks.
> 
> Best regards,
> Krzysztof
>