On Fri, 08 May 2026 06:55:04 -0700
Breno Leitao <[email protected]> wrote:
> Add a -C option that finds the "kernel" subtree of a bootconfig file
> and prints it as a flat, space-separated cmdline string by calling the
> shared xbc_snprint_cmdline() renderer. An empty or absent kernel.*
> subtree produces empty output and exits successfully.
>
> This lets the kernel build embed a bootconfig file as a plain cmdline
> string at build time, so embedded bootconfig values can reach
> parse_early_param() during architecture setup without parsing the
> bootconfig at runtime.
>
> The renderer is intentionally limited to the kernel.* subtree: that is
> the only thing the kernel build needs to embed; init.* and other
> subtrees keep going through the runtime parser.
>
> Example of this new mode:
> # cat /tmp/test.bconf
> kernel {
> foo = bar
> baz = "hello world"
> arr = 1, 2
> }
> init.foo = nope
>
> # ./tools/bootconfig/bootconfig -C /tmp/test.bconf
> foo=bar baz="hello world" arr=1 arr=2 %
>
Nice! Looks good to me. Let me pick it.
Thanks,
> Signed-off-by: Breno Leitao <[email protected]>
> ---
> tools/bootconfig/main.c | 60
> ++++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 52 insertions(+), 8 deletions(-)
>
> diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
> index 643f707b8f1da..e1bfab044fbcb 100644
> --- a/tools/bootconfig/main.c
> +++ b/tools/bootconfig/main.c
> @@ -286,7 +286,41 @@ static int init_xbc_with_error(char *buf, int len)
> return ret;
> }
>
> -static int show_xbc(const char *path, bool list)
> +static int show_xbc_kernel_cmdline(void)
> +{
> + struct xbc_node *root;
> + char *buf = NULL;
> + int len, ret;
> +
> + root = xbc_find_node("kernel");
> + if (!root)
> + return 0; /* no kernel.* keys: emit empty output */
> +
> + len = xbc_snprint_cmdline(NULL, 0, root);
> + if (len < 0) {
> + pr_err("Failed to size cmdline output: %d\n", len);
> + return len;
> + }
> + if (len == 0)
> + return 0;
> +
> + buf = malloc(len + 1);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = xbc_snprint_cmdline(buf, len + 1, root);
> + if (ret < 0) {
> + pr_err("Failed to render cmdline output: %d\n", ret);
> + free(buf);
> + return ret;
> + }
> +
> + fputs(buf, stdout);
> + free(buf);
> + return 0;
> +}
> +
> +static int show_xbc(const char *path, bool list, bool render_cmdline)
> {
> int ret, fd;
> char *buf = NULL;
> @@ -322,11 +356,14 @@ static int show_xbc(const char *path, bool list)
> if (init_xbc_with_error(buf, ret) < 0)
> goto out;
> }
> - if (list)
> + if (render_cmdline)
> + ret = show_xbc_kernel_cmdline();
> + else if (list)
> xbc_show_list();
> else
> xbc_show_compact_tree();
> - ret = 0;
> + if (ret > 0)
> + ret = 0;
> out:
> free(buf);
>
> @@ -486,7 +523,10 @@ static int usage(void)
> " Options:\n"
> " -a <config>: Apply boot config to initrd\n"
> " -d : Delete boot config file from initrd\n"
> - " -l : list boot config in initrd or file\n\n"
> + " -l : list boot config in initrd or file\n"
> + " -C : render the kernel.* subtree as a flat
> cmdline\n"
> + " string (suitable for embedding in a kernel
> image)\n"
> + " and print it to stdout\n\n"
> " If no option is given, show the bootconfig in the given
> file.\n");
> return -1;
> }
> @@ -495,10 +535,11 @@ int main(int argc, char **argv)
> {
> char *path = NULL;
> char *apply = NULL;
> + bool render_cmdline = false;
> bool delete = false, list = false;
> int opt;
>
> - while ((opt = getopt(argc, argv, "hda:l")) != -1) {
> + while ((opt = getopt(argc, argv, "hda:lC")) != -1) {
> switch (opt) {
> case 'd':
> delete = true;
> @@ -509,14 +550,17 @@ int main(int argc, char **argv)
> case 'l':
> list = true;
> break;
> + case 'C':
> + render_cmdline = true;
> + break;
> case 'h':
> default:
> return usage();
> }
> }
>
> - if ((apply && delete) || (delete && list) || (apply && list)) {
> - pr_err("Error: You can give one of -a, -d or -l at once.\n");
> + if ((!!apply + !!delete + !!list + !!render_cmdline) > 1) {
> + pr_err("Error: You can give one of -a, -d, -l or -C at
> once.\n");
> return usage();
> }
>
> @@ -532,5 +576,5 @@ int main(int argc, char **argv)
> else if (delete)
> return delete_xbc(path);
>
> - return show_xbc(path, list);
> + return show_xbc(path, list, render_cmdline);
> }
>
> --
> 2.53.0-Meta
>
>
--
Masami Hiramatsu (Google) <[email protected]>
