On 11/26/25 7:42 AM, Fabian Pflug wrote:
> The bootm.root_arg variable will be responsible for the root= part of
> the kernel commandline if bootm.appendroot is set and a root device has
> been selected.
> root_arg allows to replace the root=/dev/... with verity=/dev/..., which
> is useful in a verified boot context, where you pass the root file
> system to the initramfs, but do not want the kernel to be able to parse
> and mount the rootfs. With renaming the root= to something different,
> you make sure, that the kernel does not mount the rootfs.
>
> Signed-off-by: Fabian Pflug <[email protected]>
> ---
> common/bootm.c | 8 ++++++--
> include/bootm.h | 1 +
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/common/bootm.c b/common/bootm.c
> index 5d7dc00e3e..a1aba06f0e 100644
> --- a/common/bootm.c
> +++ b/common/bootm.c
> @@ -69,6 +69,7 @@ void bootm_data_init_defaults(struct bootm_data *data)
> data->initrd_file = getenv_nonempty("global.bootm.initrd");
> }
> data->root_dev = getenv_nonempty("global.bootm.root_dev");
> + data->root_arg = getenv_nonempty("global.bootm.root_arg");
> data->verify = bootm_get_verify_mode();
> data->appendroot = bootm_appendroot;
> data->provide_machine_id = bootm_provide_machine_id;
> @@ -88,6 +89,7 @@ void bootm_data_restore_defaults(const struct bootm_data
> *data)
> globalvar_set("bootm.initrd", data->initrd_file);
> }
> globalvar_set("bootm.root_dev", data->root_dev);
> + globalvar_set("bootm.root_arg", data->root_arg);
> bootm_set_verify_mode(data->verify);
> bootm_appendroot = data->appendroot;
> bootm_provide_machine_id = data->provide_machine_id;
> @@ -868,10 +870,10 @@ int bootm_boot(struct bootm_data *bootm_data)
> } else {
> char *rootarg;
> if(rootopts) {
> - rootarg = xasprintf("root=%s %s", root,
> rootopts);
> + rootarg = xasprintf("%s=%s %s",
> bootm_data->root_arg, root, rootopts);
> free(rootopts);
> } else {
> - rootarg = xasprintf("root=%s", root);
> + rootarg = xasprintf("%s=%s",
> bootm_data->root_arg, root);
> }
> free(root);
> pr_info("Adding \"%s\" to Kernel commandline\n",
> rootarg);
> @@ -1116,6 +1118,7 @@ static int bootm_init(void)
> globalvar_add_simple("bootm.image.loadaddr", NULL);
> globalvar_add_simple("bootm.oftree", NULL);
> globalvar_add_simple("bootm.root_dev", NULL);
> + globalvar_add_simple("bootm.root_arg", "root");
> globalvar_add_simple("bootm.tee", NULL);
> globalvar_add_simple_bool("bootm.appendroot", &bootm_appendroot);
> globalvar_add_simple_bool("bootm.earlycon", &bootm_earlycon);
> @@ -1173,5 +1176,6 @@ BAREBOX_MAGICVAR(global.bootm.verbose, "bootm default
> verbosity level (0=quiet)"
> BAREBOX_MAGICVAR(global.bootm.earlycon, "Add earlycon option to Kernel for
> early log output");
> BAREBOX_MAGICVAR(global.bootm.appendroot, "Add root= option to Kernel to
> mount rootfs from the device the Kernel comes from (default, device can be
> overridden via global.bootm.root_dev)");
> BAREBOX_MAGICVAR(global.bootm.root_dev, "bootm default root device
> (overrides default device in global.bootm.appendroot)");
> +BAREBOX_MAGICVAR(global.bootm.root_arg, "bootm default name arg for the root
> partition (normally 'root' for root=/dev/...)");
s/default name arg/default parameter name/
?
> BAREBOX_MAGICVAR(global.bootm.provide_machine_id, "If true, append
> systemd.machine_id=$global.machine_id to Kernel command line");
> BAREBOX_MAGICVAR(global.bootm.provide_hostname, "If true, append
> systemd.hostname=$global.hostname to Kernel command line");
> diff --git a/include/bootm.h b/include/bootm.h
> index b35deb25bf..43f4258885 100644
> --- a/include/bootm.h
> +++ b/include/bootm.h
> @@ -19,6 +19,7 @@ struct bootm_data {
> const char *oftree_file;
> const char *tee_file;
> const char *root_dev;
> + const char *root_arg;
> int verbose;
> enum bootm_verify verify;
> bool force;
--
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