[PATCH 1/9] powerpc: enable appending of CONFIG_CMDLINE to bootloader's cmdline.

[Christophe Leroy <christophe.leroy@c-s.fr>]

Today, powerpc defined CONFIG_CMDLINE for when bootloader doesn't
provide a command line or for overriding it.

On same way as ARM, this patch adds the option of appending the
CONFIG_CMDLINE to bootloader's provided command line.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/Kconfig                   | 21 ++++++++++++++++++++-
 arch/powerpc/kernel/prom_init.c        |  5 ++---
 arch/powerpc/kernel/prom_init_check.sh |  2 +-
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2d0be82c3061..2972348e52be 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -841,14 +841,33 @@ config CMDLINE
 	  some command-line options at build time by entering them here.  In
 	  most cases you will need to specify the root device here.
 
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FROM_BOOTLOADER
+	help
+	  Selects the way you want to use the default kernel arguments.
+
+config CMDLINE_FROM_BOOTLOADER
+	bool "Use bootloader kernel arguments if available"
+	help
+	  Uses the command-line options passed by the boot loader. If
+	  the boot loader doesn't provide any, the default kernel command
+	  string provided in CMDLINE will be used.
+
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The default kernel command string will be appended to the
+	  command-line arguments provided during boot.
+
 config CMDLINE_FORCE
 	bool "Always use the default kernel command string"
-	depends on CMDLINE_BOOL
 	help
 	  Always use the default kernel command string, even if the boot
 	  loader passes other arguments to the kernel.
 	  This is useful if you cannot or don't want to change the
 	  command-line options your boot loader passes to the kernel.
+endchoice
 
 config EXTRA_TARGETS
 	string "Additional default image types"
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index f33ff4163a51..a6cd52240c58 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -638,9 +638,8 @@ static void __init early_cmdline_parse(void)
 	if ((long)prom.chosen > 0)
 		l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
 #ifdef CONFIG_CMDLINE
-	if (l <= 0 || p[0] == '\0') /* dbl check */
-		strlcpy(prom_cmd_line,
-			CONFIG_CMDLINE, sizeof(prom_cmd_line));
+	if (l <= 0 || p[0] == '\0' || IS_ENABLED(CONFIG_CMDLINE_EXTEND)) /* dbl check */
+		strlcat(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
 #endif /* CONFIG_CMDLINE */
 	prom_printf("command line: %s\n", prom_cmd_line);
 
diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
index 667df97d2595..cbcf18846392 100644
--- a/arch/powerpc/kernel/prom_init_check.sh
+++ b/arch/powerpc/kernel/prom_init_check.sh
@@ -19,7 +19,7 @@
 WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
 _end enter_prom memcpy memset reloc_offset __secondary_hold
 __secondary_hold_acknowledge __secondary_hold_spinloop __start
-strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
+strcmp strcpy strlcat strlen strncmp strstr kstrtobool logo_linux_clut224
 reloc_got2 kernstart_addr memstart_addr linux_banner _stext
 __prom_init_toc_start __prom_init_toc_end btext_setup_display TOC."
 
-- 
2.13.3