Hi Linus,
This patch adds two boot options: rootfstype= and rootcd=.
The rootfstype= allows the user to force mounting the root filesystem of a
given type, e.g. to resolve ambiguity between filesystem types which store
superblocks at different locations or use the same magic number
(e.g. umsdos vx vfat)
The rootfstype= boot option was discussed on the list ages ago and
everyone seems to agree it is useful.
The rootcd= option allows mounting the root filesystem on the first CD-ROM
in the absence of devfs in a device-independent way (so that users don't
need to supply the correct root= e.g. when booting a Linux Demo with a
live root filesystem on a CD-ROM).
Regards,
Tigran
diff -urN -X dontdiff linux/Documentation/kernel-parameters.txt linux-b/Documentation/kernel-parameters.txt
--- linux/Documentation/kernel-parameters.txt Wed Jun 20 19:21:33 2001
+++ linux-b/Documentation/kernel-parameters.txt Mon Jul 23 10:56:56 2001
@@ -504,8 +504,13 @@
ro [KNL] Mount root device read-only on boot.
- root= [KNL] root filesystem.
+ root= [KNL] Where to mount root filesystem.
+
+ rootfstype= [KNL] Only mount root filesystem of this type.
+
+ rootcd= [KNL] Mount root on the first CD-ROM if != 0
+
rw [KNL] Mount root device read-write on boot.
S [KNL] run init in single mode.
diff -urN -X dontdiff linux/drivers/cdrom/cdrom.c linux-b/drivers/cdrom/cdrom.c
--- linux/drivers/cdrom/cdrom.c Wed Jul 11 22:55:41 2001
+++ linux-b/drivers/cdrom/cdrom.c Mon Jul 23 11:04:03 2001
@@ -2494,6 +2494,11 @@
return proc_dostring(ctl, write, filp, buffer, lenp);
}
+kdev_t get_cdrom_dev(void)
+{
+ return topCdromPtr ? topCdromPtr->dev : 0;
+}
+
/* Unfortunately, per device settings are not implemented through
procfs/sysctl yet. When they are, this will naturally disappear. For now
just update all drives. Later this will become the template on which
diff -urN -X dontdiff linux/fs/super.c linux-b/fs/super.c
--- linux/fs/super.c Thu Jun 14 22:16:58 2001
+++ linux-b/fs/super.c Mon Jul 23 11:02:35 2001
@@ -18,6 +18,7 @@
* Torbj?rn Lindh ([email protected]), April 14, 1996.
* Added devfs support: Richard Gooch <[email protected]>, 13-JAN-1998
* Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
+ * Added rootfstype boot param. used by mount_root(): Tigran Aivazian. July 2001.
*/
#include <linux/config.h>
@@ -59,6 +60,12 @@
/* this is initialized in init/main.c */
kdev_t ROOT_DEV;
+/* this can be set at boot time, e.g. rootfstype=umsdos
+ * if set to invalid value or if read_super() fails on the specified
+ * filesystem type then mount_root() will panic
+ */
+static char rootfstype[32] __initdata = "";
+
int nr_super_blocks;
int max_super_blocks = NR_SUPER;
LIST_HEAD(super_blocks);
@@ -79,6 +86,18 @@
static struct file_system_type *file_systems;
static rwlock_t file_systems_lock = RW_LOCK_UNLOCKED;
+static int __init rootfstype_setup(char *line)
+{
+ int n = strlen(line) + 1;
+
+ if (n > 1 && n <= sizeof(rootfstype))
+ strncpy(rootfstype, line, n);
+ return 1;
+}
+
+__setup("rootfstype=", rootfstype_setup);
+
+
/* WARNING: This can be used only if we _already_ own a reference */
static void get_filesystem(struct file_system_type *fs)
{
@@ -1587,6 +1606,17 @@
goto mount_it;
}
+ if (*rootfstype) {
+ fs_type = get_fs_type(rootfstype);
+ if (fs_type) {
+ sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,NULL,1);
+ if (sb)
+ goto mount_it;
+ }
+ /* don't try others if type given explicitly, same behaviour as mount(8) */
+ goto fail;
+ }
+
read_lock(&file_systems_lock);
for (fs_type = file_systems ; fs_type ; fs_type = fs_type->next) {
if (!(fs_type->fs_flags & FS_REQUIRES_DEV))
@@ -1601,7 +1631,9 @@
put_filesystem(fs_type);
}
read_unlock(&file_systems_lock);
- panic("VFS: Unable to mount root fs on %s", kdevname(ROOT_DEV));
+fail:
+ panic("VFS: Unable to mount root %s on %s",
+ *rootfstype ? rootfstype : "fs", kdevname(ROOT_DEV));
mount_it:
printk ("VFS: Mounted root (%s filesystem)%s.\n",
diff -urN -X dontdiff linux/init/main.c linux-b/init/main.c
--- linux/init/main.c Thu Jul 5 19:31:58 2001
+++ linux-b/init/main.c Mon Jul 23 11:03:25 2001
@@ -304,6 +304,16 @@
__setup("root=", root_dev_setup);
+static int rootcd_enable __initdata = 0;
+
+static int __init rootcd_setup(char *str)
+{
+ get_option(&str, &rootcd_enable);
+ return 1;
+}
+
+__setup("rootcd=", rootcd_setup);
+
static int __init checksetup(char *line)
{
struct kernel_param *p;
@@ -745,6 +755,11 @@
#endif
rd_load();
#endif
+
+ if (rootcd_enable) {
+ extern kdev_t get_cdrom_dev(void);
+ ROOT_DEV = get_cdrom_dev();
+ }
/* Mount the root filesystem.. */
mount_root();
Tigran Aivazian wrote:
>
> Hi Linus,
>
> This patch adds two boot options: rootfstype= and rootcd=.
>
That would be useful for ext2/ext3 interoperability too.
ext3 also need to ability to pass mount options to the
root fs. Any chance of munging these two things together?
--- linux-2.4.7/fs/super.c Wed Jul 4 18:21:31 2001
+++ lk-ext3/fs/super.c Fri Jun 29 02:09:31 2001
@@ -1467,6 +1467,17 @@ out1:
return retval;
}
+static char *root_mount_data;
+static int __init root_data_setup(char *line)
+{
+ static char buffer[128];
+
+ strcpy(buffer, line);
+ root_mount_data = buffer;
+ return 1;
+}
+__setup("rootflags=", root_data_setup);
+
void __init mount_root(void)
{
struct file_system_type * fs_type;
@@ -1594,7 +1605,8 @@ skip_nfs:
if (!try_inc_mod_count(fs_type->owner))
continue;
read_unlock(&file_systems_lock);
- sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,NULL,1);
+ sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,
+ root_mount_data,1);
if (sb)
goto mount_it;
read_lock(&file_systems_lock);
On Mon, 23 Jul 2001, Andrew Morton wrote:
> ext3 also need to ability to pass mount options to the
> root fs. Any chance of munging these two things together?
Linus,
here is the patch with Andrew's suggested stuff added.
Regards,
Tigran
diff -urN -X dontdiff linux/Documentation/kernel-parameters.txt linux-b/Documentation/kernel-parameters.txt
--- linux/Documentation/kernel-parameters.txt Wed Jun 20 19:21:33 2001
+++ linux-b/Documentation/kernel-parameters.txt Mon Jul 23 13:54:07 2001
@@ -504,8 +504,15 @@
ro [KNL] Mount root device read-only on boot.
- root= [KNL] root filesystem.
+ root= [KNL] Where to mount root filesystem.
+
+ rootfstype= [KNL] Only mount root filesystem of this type.
+
+ rootflags= [KNL] Mount options for root filesystem
+
+ rootcd= [KNL] Mount root on the first CD-ROM if != 0
+
rw [KNL] Mount root device read-write on boot.
S [KNL] run init in single mode.
diff -urN -X dontdiff linux/drivers/cdrom/cdrom.c linux-b/drivers/cdrom/cdrom.c
--- linux/drivers/cdrom/cdrom.c Wed Jul 11 22:55:41 2001
+++ linux-b/drivers/cdrom/cdrom.c Mon Jul 23 13:50:34 2001
@@ -2494,6 +2494,11 @@
return proc_dostring(ctl, write, filp, buffer, lenp);
}
+kdev_t get_cdrom_dev(void)
+{
+ return topCdromPtr ? topCdromPtr->dev : 0;
+}
+
/* Unfortunately, per device settings are not implemented through
procfs/sysctl yet. When they are, this will naturally disappear. For now
just update all drives. Later this will become the template on which
diff -urN -X dontdiff linux/fs/super.c linux-b/fs/super.c
--- linux/fs/super.c Thu Jun 14 22:16:58 2001
+++ linux-b/fs/super.c Mon Jul 23 13:52:47 2001
@@ -18,6 +18,7 @@
* Torbj?rn Lindh ([email protected]), April 14, 1996.
* Added devfs support: Richard Gooch <[email protected]>, 13-JAN-1998
* Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
+ * Added rootfstype boot param. used by mount_root(): Tigran Aivazian. July 2001.
*/
#include <linux/config.h>
@@ -59,6 +60,12 @@
/* this is initialized in init/main.c */
kdev_t ROOT_DEV;
+/* this can be set at boot time, e.g. rootfstype=umsdos
+ * if set to invalid value or if read_super() fails on the specified
+ * filesystem type then mount_root() will panic
+ */
+static char rootfstype[32] __initdata = "";
+
int nr_super_blocks;
int max_super_blocks = NR_SUPER;
LIST_HEAD(super_blocks);
@@ -79,6 +86,18 @@
static struct file_system_type *file_systems;
static rwlock_t file_systems_lock = RW_LOCK_UNLOCKED;
+static int __init rootfstype_setup(char *line)
+{
+ int n = strlen(line) + 1;
+
+ if (n > 1 && n <= sizeof(rootfstype))
+ strncpy(rootfstype, line, n);
+ return 1;
+}
+
+__setup("rootfstype=", rootfstype_setup);
+
+
/* WARNING: This can be used only if we _already_ own a reference */
static void get_filesystem(struct file_system_type *fs)
{
@@ -1467,6 +1486,18 @@
return retval;
}
+static char *root_mount_data;
+
+static int __init root_data_setup(char *line)
+{
+ static char buffer[128];
+
+ strcpy(buffer, line);
+ root_mount_data = buffer;
+ return 1;
+}
+__setup("rootflags=", root_data_setup);
+
void __init mount_root(void)
{
struct file_system_type * fs_type;
@@ -1587,6 +1618,18 @@
goto mount_it;
}
+ if (*rootfstype) {
+ fs_type = get_fs_type(rootfstype);
+ if (fs_type) {
+ sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,
+ root_mount_data,1);
+ if (sb)
+ goto mount_it;
+ }
+ /* don't try others if type given explicitly, same behaviour as mount(8) */
+ goto fail;
+ }
+
read_lock(&file_systems_lock);
for (fs_type = file_systems ; fs_type ; fs_type = fs_type->next) {
if (!(fs_type->fs_flags & FS_REQUIRES_DEV))
@@ -1594,14 +1637,17 @@
if (!try_inc_mod_count(fs_type->owner))
continue;
read_unlock(&file_systems_lock);
- sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,NULL,1);
+ sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,
+ root_mount_data,1);
if (sb)
goto mount_it;
read_lock(&file_systems_lock);
put_filesystem(fs_type);
}
read_unlock(&file_systems_lock);
- panic("VFS: Unable to mount root fs on %s", kdevname(ROOT_DEV));
+fail:
+ panic("VFS: Unable to mount root %s on %s",
+ *rootfstype ? rootfstype : "fs", kdevname(ROOT_DEV));
mount_it:
printk ("VFS: Mounted root (%s filesystem)%s.\n",
diff -urN -X dontdiff linux/init/main.c linux-b/init/main.c
--- linux/init/main.c Thu Jul 5 19:31:58 2001
+++ linux-b/init/main.c Mon Jul 23 13:50:34 2001
@@ -304,6 +304,16 @@
__setup("root=", root_dev_setup);
+static int rootcd_enable __initdata = 0;
+
+static int __init rootcd_setup(char *str)
+{
+ get_option(&str, &rootcd_enable);
+ return 1;
+}
+
+__setup("rootcd=", rootcd_setup);
+
static int __init checksetup(char *line)
{
struct kernel_param *p;
@@ -745,6 +755,11 @@
#endif
rd_load();
#endif
+
+ if (rootcd_enable) {
+ extern kdev_t get_cdrom_dev(void);
+ ROOT_DEV = get_cdrom_dev();
+ }
/* Mount the root filesystem.. */
mount_root();