wok annotate linux/stuff/linux-subroot.u @ rev 14760

linux: add boot subroot support (again)
author Pascal Bellard <pascal.bellard@slitaz.org>
date Wed Jun 19 11:55:19 2013 +0200 (2013-06-19)
parents 1472150d52c4
children c6e93d1e6bac
rev   line source
pascal@14760 1 Allow to boot on any directories in a filesystem. You will be able to :
pascal@14760 2 - have several distributions in one partition
pascal@14760 3 - use efficently the disk space between several distributions
pascal@14760 4 - deduplicate files across several distributions
pascal@14760 5 - test new configurations
pascal@14760 6 ...
pascal@14759 7 --- linux-3.2.40/Documentation/kernel-parameters.txt
pascal@14759 8 +++ linux-3.2.40/Documentation/kernel-parameters.txt
pascal@14759 9 @@ -2304,8 +2304,9 @@
pascal@14759 10
pascal@14759 11 ro [KNL] Mount root device read-only on boot
pascal@14759 12
pascal@14759 13 - root= [KNL] Root filesystem
pascal@14759 14 + root= [KNL] Root filesystem and root directory
pascal@14759 15 See name_to_dev_t comment in init/do_mounts.c.
pascal@14759 16 + Format: <root_filesystem>[:root_directory]
pascal@14759 17
pascal@14759 18 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
pascal@14759 19 mount the root filesystem
pascal@14759 20 --- linux-3.2.40/init/do_mounts.c
pascal@14759 21 +++ linux-3.2.40/init/do_mounts.c
pascal@14759 22 @@ -28,6 +28,7 @@
pascal@14759 23 int root_mountflags = MS_RDONLY | MS_SILENT;
pascal@14759 24 static char * __initdata root_device_name;
pascal@14759 25 static char __initdata saved_root_name[64];
pascal@14759 26 +static char __initdata saved_root_directory[256];
pascal@14759 27 static int root_wait;
pascal@14759 28
pascal@14759 29 dev_t ROOT_DEV;
pascal@14759 30 @@ -255,7 +256,20 @@
pascal@14759 31
pascal@14759 32 static int __init root_dev_setup(char *line)
pascal@14759 33 {
pascal@14759 34 + char *s;
pascal@14759 35 +
pascal@14759 36 + strcpy(saved_root_directory, ".");
pascal@14759 37 strlcpy(saved_root_name, line, sizeof(saved_root_name));
pascal@14759 38 + s = strchr(saved_root_name, ':');
pascal@14759 39 + if (s) {
pascal@14759 40 + *s = '\0';
pascal@14759 41 + s = strchr(line, ':');
pascal@14759 42 + for (s++; *s == '/'; s++);
pascal@14759 43 + if (*s) {
pascal@14759 44 + strlcpy(saved_root_directory, s,
pascal@14759 45 + sizeof(saved_root_directory));
pascal@14759 46 + }
pascal@14759 47 + }
pascal@14759 48 return 1;
pascal@14759 49 }
pascal@14759 50
pascal@14759 51 @@ -554,5 +568,5 @@
pascal@14759 52 out:
pascal@14759 53 devtmpfs_mount("dev");
pascal@14759 54 sys_mount(".", "/", NULL, MS_MOVE, NULL);
pascal@14759 55 - sys_chroot((const char __user __force *)".");
pascal@14759 56 + sys_chroot((const char __user __force *)saved_root_directory);
pascal@14759 57 }