Currently, "bootargs" supplied via the "chosen" node can be used only to
supply a kernel command line as a whole. No mechanism exists in DT to add
bootargs to the existing command line instead. This is needed in order to
avoid having to update the bootloader or default bootloader config when
upgrading to a DTB and kernel pair that requires bootargs not previously
needed.
One example use case is that OpenWrt currently supports four ARM devices by
means of locally applying the previously rejected edition of this patch. So
far, the patch has been used in production only on ARM, but architecture is
not a distinction in the design.
On MIPS, Commit 951d223 ("MIPS: Fix CONFIG_CMDLINE handling") currently
prevents support of such a mechanism, so I am including a workaround, in
anticipation of upcoming changes.
Signed-off-by: Daniel Gimpelevich <daniel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Fixes: 951d223 ("MIPS: Fix CONFIG_CMDLINE handling")
References: https://patchwork.linux-mips.org/patch/17659/
---
arch/mips/kernel/setup.c | 12 ++++++++----
drivers/of/fdt.c | 9 +++++++--
2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index ab349d2..9ce58f2 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -725,7 +725,10 @@ static void __init arch_mem_init(char **cmdline_p)
* CONFIG_CMDLINE ourselves below & don't want to duplicate its
* content because repeating arguments can be problematic.
*/
- strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
+ if (USE_DTB_CMDLINE)
+ strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
+ else
+ strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
/* call board setup routine */
plat_mem_setup();
@@ -753,9 +756,10 @@ static void __init arch_mem_init(char **cmdline_p)
#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
#else
- if ((USE_PROM_CMDLINE && arcs_cmdline[0]) ||
- (USE_DTB_CMDLINE && !boot_command_line[0]))
+ if (USE_PROM_CMDLINE)
strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
+ else if (!strcmp(boot_command_line, " "))
+ boot_command_line[0] = '\0';
if (EXTEND_WITH_PROM && arcs_cmdline[0]) {
if (boot_command_line[0])
@@ -764,7 +768,7 @@ static void __init arch_mem_init(char **cmdline_p)
}
#if defined(CONFIG_CMDLINE_BOOL)
- if (builtin_cmdline[0]) {
+ if (builtin_cmdline[0] && strcmp(boot_command_line, builtin_cmdline)) {
if (boot_command_line[0])
strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 9cdf14b..08c25eb 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1055,8 +1055,13 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
/* Retrieve command line */
p = of_get_flat_dt_prop(node, "bootargs", &l);
- if (p != NULL && l > 0)
- strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
+ if (p != NULL && l > 0) {
+ if (!of_get_flat_dt_prop(node, "merge-cmdline", NULL))
+ *(char *)data = '\0';
+ if (*(char *)data)
+ strlcat(data, " ", COMMAND_LINE_SIZE);
+ strlcat(data, p, min(l + strlen(data), COMMAND_LINE_SIZE));
+ }
/*
* CONFIG_CMDLINE is meant to be a default in case nothing else
--
1.9.1
