[PATCH 2/3] init: use static buffers for bootconfig extra command line

Breno Leitao
2026-04-15T10:51:28Z

Replace memblock_alloc/memblock_free in xbc_make_cmdline() with
static __initdata buffers. This removes the last memblock dependency
from the bootconfig loading path, completing the prerequisite for
running bootconfig parsing before memblock is available.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
init/main.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/init/main.c b/init/main.c
index 96f93bb06c490..b9feca55e01f9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -369,11 +369,18 @@ static int __init xbc_snprint_cmdline(char *buf, size_t size,
}
#undef rest

+/*
+ * Static buffers for bootconfig-generated command line parameters.
+ * Two separate buffers are needed because both "kernel" and "init"
+ * parameters are stored simultaneously.
+ */
+static char extra_cmdline_buf[COMMAND_LINE_SIZE] __initdata;
+static char extra_initargs_buf[COMMAND_LINE_SIZE] __initdata;
+
/* Make an extra command line under given key word */
-static char * __init xbc_make_cmdline(const char *key)
+static char * __init xbc_make_cmdline(const char *key, char *new_cmdline)
{
struct xbc_node *root;
- char *new_cmdline;
int ret, len = 0;

root = xbc_find_node(key);
@@ -382,19 +389,12 @@ static char * __init xbc_make_cmdline(const char *key)

/* Count required buffer size */
len = xbc_snprint_cmdline(NULL, 0, root);
- if (len <= 0)
+ if (len <= 0 || len >= COMMAND_LINE_SIZE)
return NULL;

- new_cmdline = memblock_alloc(len + 1, SMP_CACHE_BYTES);
- if (!new_cmdline) {
- pr_err("Failed to allocate memory for extra kernel cmdline.\n");
- return NULL;
- }
-
ret = xbc_snprint_cmdline(new_cmdline, len + 1, root);
if (ret < 0 || ret > len) {
pr_err("Failed to print extra kernel cmdline.\n");
- memblock_free(new_cmdline, len + 1);
return NULL;
}

@@ -467,9 +467,9 @@ static void __init setup_boot_config(void)
xbc_get_info(&ret, NULL);
pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
/* keys starting with "kernel." are passed via cmdline */
- extra_command_line = xbc_make_cmdline("kernel");
+ extra_command_line = xbc_make_cmdline("kernel", extra_cmdline_buf);
/* Also, "init." keys are init arguments */
- extra_init_args = xbc_make_cmdline("init");
+ extra_init_args = xbc_make_cmdline("init", extra_initargs_buf);
}
return;
}

--
2.52.0