It becomes a common case that the Kernel is loaded from the filesystem which later becomes the rootfs. This adds a possibility to let bootm automatically append the root= option to the kernel command line. This is done when global.bootm.appendroot is true. Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> --- Documentation/user/booting-linux.rst | 14 ++++++++++++++ commands/bootm.c | 1 + common/bootm.c | 17 +++++++++++++++++ include/boot.h | 5 +++++ 4 files changed, 37 insertions(+) diff --git a/Documentation/user/booting-linux.rst b/Documentation/user/booting-linux.rst index 98628fa..f26299e 100644 --- a/Documentation/user/booting-linux.rst +++ b/Documentation/user/booting-linux.rst @@ -99,6 +99,20 @@ with addpart to the Kernel: Kernel command line: mtdparts=physmap-flash.0:512k(bootloader),512k(env),4M(kernel),-(root); mxc_nand:1M(bootloader),1M(env),4M(kernel),-(root) +Creating root= options for the Kernel +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +It's a common case that the Linux Kernel is loaded from a filesystem +that later becomes the root filesystem for the Kernel. For several +filesystems barebox can automatically append a suitable root= option +to the Kernel command line. This is done when ``global.bootm.appendroot`` +is true. How the root= option is appended depends on the device type +and filesystem the kernel is booted from. For disk like devices (SD/MMC, +ATA) the partition UUID will be used, the root= option will be something +like ``root=PARTUUID=deadbeef-1``. For UBIFS fileystems it will be +``root=ubi0:volname ubi.mtd=mtdpartname rootfstype=ubifs``. NFS +filesystems will result in ``root=/dev/nfs nfsroot=ip:/path/to/nfsroot,v3,tcp``. +The ``v3,tcp`` part is configurable in ``global.linux.rootnfsopts``. The boot command ---------------- diff --git a/commands/bootm.c b/commands/bootm.c index 7a19fa2..bfec62c 100644 --- a/commands/bootm.c +++ b/commands/bootm.c @@ -166,6 +166,7 @@ BAREBOX_MAGICVAR_NAMED(global_bootm_initrd, global.bootm.initrd, "bootm default BAREBOX_MAGICVAR_NAMED(global_bootm_initrd_loadaddr, global.bootm.initrd.loadaddr, "bootm default initrd loadaddr"); BAREBOX_MAGICVAR_NAMED(global_bootm_oftree, global.bootm.oftree, "bootm default oftree"); BAREBOX_MAGICVAR_NAMED(global_bootm_verify, global.bootm.verify, "bootm default verify level"); +BAREBOX_MAGICVAR_NAMED(global_bootm_appendroot, global.bootm.appendroot, "Add root= option to Kernel to mount rootfs from the device the Kernel comes from"); static struct binfmt_hook binfmt_uimage_hook = { .type = filetype_uimage, diff --git a/common/bootm.c b/common/bootm.c index 6d22aab..cad8c73 100644 --- a/common/bootm.c +++ b/common/bootm.c @@ -48,6 +48,8 @@ static struct image_handler *bootm_find_handler(enum filetype filetype, return NULL; } +static int bootm_appendroot; + void bootm_data_init_defaults(struct bootm_data *data) { data->initrd_address = UIMAGE_INVALID_ADDRESS; @@ -58,6 +60,7 @@ void bootm_data_init_defaults(struct bootm_data *data) getenv_ul("global.bootm.initrd.loadaddr", &data->initrd_address); data->initrd_file = getenv_nonempty("global.bootm.initrd"); data->verify = bootm_get_verify_mode(); + data->appendroot = bootm_appendroot; } static enum bootm_verify bootm_verify_mode = BOOTM_VERIFY_HASH; @@ -576,6 +579,18 @@ int bootm_boot(struct bootm_data *bootm_data) } } + if (bootm_data->appendroot) { + char *rootarg; + + rootarg = path_get_linux_rootarg(data->os_file); + if (!IS_ERR(rootarg)) { + printf("Adding \"%s\" to Kernel commandline\n", rootarg); + globalvar_add_simple("linux.bootargs.bootm.appendroot", + rootarg); + free(rootarg); + } + } + printf("\nLoading %s '%s'", file_type_to_string(os_type), data->os_file); if (os_type == filetype_uimage && @@ -621,6 +636,7 @@ err_out: if (data->of_root_node && data->of_root_node != of_get_root_node()) of_delete_node(data->of_root_node); + globalvar_remove("linux.bootargs.bootm.appendroot"); free(data->os_file); free(data->oftree_file); free(data->initrd_file); @@ -634,6 +650,7 @@ static int bootm_init(void) globalvar_add_simple("bootm.image", NULL); globalvar_add_simple("bootm.image.loadaddr", NULL); globalvar_add_simple("bootm.oftree", NULL); + globalvar_add_simple_bool("bootm.appendroot", &bootm_appendroot); if (IS_ENABLED(CONFIG_CMD_BOOTM_INITRD)) { globalvar_add_simple("bootm.initrd", NULL); globalvar_add_simple("bootm.initrd.loadaddr", NULL); diff --git a/include/boot.h b/include/boot.h index 0198cc8..8fcbb7f 100644 --- a/include/boot.h +++ b/include/boot.h @@ -21,6 +21,11 @@ struct bootm_data { enum bootm_verify verify; bool force; bool dryrun; + /* + * appendroot - if true, try to add a suitable root= Kernel option to + * mount the rootfs from the same device as the Kernel comes from. + */ + bool appendroot; unsigned long initrd_address; unsigned long os_address; unsigned long os_entry; -- 2.8.0.rc3 _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox