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SubjectRe: [PATCH v3 01/17] cmdline: Add generic function to build command line.
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Le 26/03/2021 à 16:42, Rob Herring a écrit :
> On Fri, Mar 26, 2021 at 7:44 AM Christophe Leroy
> <christophe.leroy@csgroup.eu> 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.
>
> Note that I have this patch pending:
>
> https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20210316193820.3137-1-alex@ghiti.fr/
>
> It's going to need to be adapted for this. I've held off applying to
> see if this gets settled.

good point.

Hope we can't have things like

option="beautiful weather"

>
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>> 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.
>> + */
>> +static __always_inline void __cmdline_build(char *dst, const char *src, size_t len)
>> +{
>> + if (!len || src == dst)
>> + return;
>> +
>> + if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !src) {
>> + dst[0] = 0;
>> + cmdline_strlcat(dst, CONFIG_CMDLINE, len);
>> + return;
>> + }
>> +
>> + if (dst != src)
>> + dst[0] = 0;
>> +
>> + if (IS_ENABLED(CONFIG_CMDLINE_PREPEND))
>> + cmdline_strlcat(dst, CONFIG_CMDLINE " ", len);
>> +
>> + cmdline_strlcat(dst, src, len);
>> +
>> + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND))
>
> Should be APPEND.

Not yet. For the time being all architectures use EXTEND only.

In patch 3 it is changed to:

- if (IS_ENABLED(CONFIG_CMDLINE_EXTEND))
+ if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || IS_ENABLED(CONFIG_CMDLINE_APPEND))

Then in last patch, I forgot but I should have done:

- if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || IS_ENABLED(CONFIG_CMDLINE_APPEND))
+ if (IS_ENABLED(CONFIG_CMDLINE_APPEND))


>
>> + cmdline_strlcat(dst, " " CONFIG_CMDLINE, len);
>> +}
>> +
>> +#define cmdline_build(dst, src, len) do { \
>
> Perhaps a comment why we need this to be a define.

Probably we don't need anymore as I finally decided to use COMMAND_LINE_SIZE instead of 'len' as the
size of the temporary buffer.

>
>> + char *__c_dst = (dst); \
>> + const char *__c_src = (src); \
>> + \
>> + if (__c_src == __c_dst) { \
>> + static char __c_tmp[COMMAND_LINE_SIZE] __initdata = ""; \
>> + \
>> + cmdline_strlcat(__c_tmp, __c_src, COMMAND_LINE_SIZE); \
>> + __cmdline_build(__c_dst, __c_tmp, (len)); \
>> + } else { \
>> + __cmdline_build(__c_dst, __c_src, (len)); \
>> + } \
>> +} while (0)
>> +
>> +#endif /* _LINUX_CMDLINE_H */
>> --
>> 2.25.0
>>

Christophe

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