This patch is taken from OpenWrt, see: https://github.com/openwrt/openwrt/blob/master/package/boot/grub2/patches/100-grub_setup_root.patch. It allows to use grub-bios-setup on a raw disk-images, without root permissions. --- a/util/grub-setup.c +++ b/util/grub-setup.c @@ -87,6 +87,8 @@ static struct argp_option options[] = { N_("install even if problems are detected"), 0}, {"skip-fs-probe",'s',0, 0, N_("do not probe for filesystems in DEVICE"), 0}, + {"root-device", 'r', N_("DEVICE"), 0, + N_("use DEVICE as the root device"), 0}, {"verbose", 'v', 0, 0, N_("print verbose messages."), 0}, {"allow-floppy", 'a', 0, 0, /* TRANSLATORS: The potential breakage isn't limited to floppies but it's @@ -130,6 +132,7 @@ struct arguments char *core_file; char *dir; char *dev_map; + char *root_dev; int force; int fs_probe; int allow_floppy; @@ -178,6 +181,13 @@ argp_parser (int key, char *arg, struct arguments->dev_map = xstrdup (arg); break; + case 'r': + if (arguments->root_dev) + free (arguments->root_dev); + + arguments->root_dev = xstrdup (arg); + break; + case 'f': arguments->force = 1; break; @@ -313,7 +323,7 @@ main (int argc, char *argv[]) GRUB_SETUP_FUNC (arguments.dir ? : DEFAULT_DIRECTORY, arguments.boot_file ? : DEFAULT_BOOT_FILE, arguments.core_file ? : DEFAULT_CORE_FILE, - dest_dev, arguments.force, + arguments.root_dev, dest_dev, arguments.force, arguments.fs_probe, arguments.allow_floppy, arguments.add_rs_codes); --- a/util/setup.c +++ b/util/setup.c @@ -252,13 +252,12 @@ identify_partmap (grub_disk_t disk __att void SETUP (const char *dir, const char *boot_file, const char *core_file, - const char *dest, int force, + char *root, const char *dest, int force, int fs_probe, int allow_floppy, int add_rs_codes __attribute__ ((unused))) /* unused on sparc64 */ { char *core_path; char *boot_img, *core_img, *boot_path; - char *root = 0; size_t boot_size, core_size; grub_uint16_t core_sectors; grub_device_t root_dev = 0, dest_dev, core_dev; @@ -307,7 +306,10 @@ SETUP (const char *dir, core_dev = dest_dev; - { + if (root) + root_dev = grub_device_open(root); + + if (!root_dev) { char **root_devices = grub_guess_root_devices (dir); char **cur; int found = 0; @@ -320,6 +322,8 @@ SETUP (const char *dir, char *drive; grub_device_t try_dev; + if (root_dev) + break; drive = grub_util_get_grub_dev (*cur); if (!drive) continue; --- a/include/grub/util/install.h +++ b/include/grub/util/install.h @@ -191,13 +191,13 @@ grub_install_get_image_target (const cha void grub_util_bios_setup (const char *dir, const char *boot_file, const char *core_file, - const char *dest, int force, + char *root, const char *dest, int force, int fs_probe, int allow_floppy, int add_rs_codes); void grub_util_sparc_setup (const char *dir, const char *boot_file, const char *core_file, - const char *dest, int force, + char *root, const char *dest, int force, int fs_probe, int allow_floppy, int add_rs_codes); --- a/util/grub-install.c +++ b/util/grub-install.c @@ -1712,7 +1712,7 @@ main (int argc, char *argv[]) /* Now perform the installation. */ if (install_bootsector) grub_util_bios_setup (platdir, "boot.img", "core.img", - install_drive, force, + NULL, install_drive, force, fs_probe, allow_floppy, add_rs_codes); break; } @@ -1738,7 +1738,7 @@ main (int argc, char *argv[]) /* Now perform the installation. */ if (install_bootsector) grub_util_sparc_setup (platdir, "boot.img", "core.img", - install_drive, force, + NULL, install_drive, force, fs_probe, allow_floppy, 0 /* unused */ ); break;