# Re: \[PATCH v3 01/17\] cmdline: Add generic function to build command line.

- From: Christophe Leroy \<hidden\>
- Date: 2021-04-02 15:33:15 
- List: linux-devicetree
- Page: https://ratatoskr.run/linux-devicetree/2021/04/6325386
- Thread: https://ratatoskr.run/linux-arch/2021/03/6316694/t.md

```text


Le 30/03/2021 à 19:27, Daniel Walker a écrit :
> On Fri, Mar 26, 2021 at 01:44:48PM +0000, Christophe Leroy wrote:
>> This code provides architectures with a way to build command line
>> based on what is built in the kernel and what is handed over by the
>> bootloader, based on selected compile-time options.
>>
>> Signed-off-by: Christophe Leroy <redacted>
>> ---
>> v3:
>> - Addressed comments from Will
>> - Added capability to have src == dst
>> ---
>>   include/linux/cmdline.h | 57 +++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 57 insertions(+)
>>   create mode 100644 include/linux/cmdline.h
>>
>> diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h
>> new file mode 100644
>> index 000000000000..dea87edd41be
>> --- /dev/null
>> +++ b/include/linux/cmdline.h
>> @@ -0,0 +1,57 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#ifndef _LINUX_CMDLINE_H
>> +#define _LINUX_CMDLINE_H
>> +
>> +#include <linux/string.h>
>> +
>> +/* Allow architectures to override strlcat, powerpc can't use strings so early */
>> +#ifndef cmdline_strlcat
>> +#define cmdline_strlcat strlcat
>> +#endif
>> +
>> +/*
>> + * This function will append or prepend a builtin command line to the command
>> + * line provided by the bootloader. Kconfig options can be used to alter
>> + * the behavior of this builtin command line.
>> + * @dst: The destination of the final appended/prepended string.
>> + * @src: The starting string or NULL if there isn't one.
>> + * @len: the length of dest buffer.
>> + */
>
> Append or prepend ? Cisco requires both at the same time. This is why my
> implementation provides both. I can't use this with both at once.
>

I think it can be added as a second step if dimmed necessary. The feeling I have from all the discussion is that it's not what people from the community are looking for at the moment.

Anyway, once all architectures are moved to generic handling, I believe it is then easier to split CONFIG_CMDLINE in two configuration items in order to provide both appending and prepending at the same time.

I see some concerns about risk of double changes, but I have focussed in changing as little as possible the existing configuration items, in order to minimise that.
```