Le 26/03/2021 à 16:42, Rob Herring a écrit :

On Fri, Mar 26, 2021 at 7:44 AM Christophe Leroy
[off-list ref] wrote:

quoted

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"

quoted

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.
+ */
+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))

quoted

+               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.

quoted

+       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