Is this still strictly necessary? I thought the guys booting with a
root using virtfs didn't need this -- but perhaps their approach
depends on specific configurations in an initrd and this doesn't?
-eric
(Add cc: linux-fs and cc: linux-kernel)
On Mon, May 14, 2012 at 9:29 AM, Ian Kirk <blob@xxxxxxxxxx> wrote:
> This patch adds support for running a 9P filesystem as root using a method
> similar to NFS root. Passing root=9p to the Kernel command line works
> in a comparable way to passing root=nfs
>
> Signed-off-by: Ian Kirk <blob@xxxxxxxxxx>
> ---
> fs/9p/Kconfig | 7 +++++++
> include/linux/root_dev.h | 1 +
> init/do_mounts.c | 25 +++++++++++++++++++++++++
> 3 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/fs/9p/Kconfig b/fs/9p/Kconfig
> index 0a93dc1..ffd73f5 100644
> --- a/fs/9p/Kconfig
> +++ b/fs/9p/Kconfig
> @@ -31,4 +31,11 @@ config 9P_FS_POSIX_ACL
>
> If you don't know what Access Control Lists are, say N
>
> +config ROOT_9P
> + bool "9p root filesystem"
> + depends on 9P_FS=m || 9P_FS=y
> + help
> + Permits you to pass root=9p to the kernel command line and have the
> + root filesystem on 9p
> +
> endif
> diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h
> index ed241aa..61633ed 100644
> --- a/include/linux/root_dev.h
> +++ b/include/linux/root_dev.h
> @@ -7,6 +7,7 @@
>
> enum {
> Root_NFS = MKDEV(UNNAMED_MAJOR, 255),
> + Root_9P = MKDEV(UNNAMED_MAJOR, 254),
> Root_RAM0 = MKDEV(RAMDISK_MAJOR, 0),
> Root_RAM1 = MKDEV(RAMDISK_MAJOR, 1),
> Root_FD0 = MKDEV(FLOPPY_MAJOR, 0),
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index 2974c8b..4ec8dce 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -212,6 +212,9 @@ dev_t name_to_dev_t(char *name)
> res = Root_RAM0;
> if (strcmp(name, "ram") == 0)
> goto done;
> + res = Root_9P;
> + if (strcmp(name, "9p") == 0)
> + goto done;
>
> if (strlen(name) > 31)
> goto fail;
> @@ -439,6 +442,18 @@ static int __init mount_nfs_root(void)
> }
> #endif
>
> +#ifdef CONFIG_ROOT_9P
> +static int __init mount_9p_root(void)
> +{
> + int err = do_mount_root("root", "9p", root_mountflags, root_mount_data);
> +
> + if (err == 0)
> + return 1;
> +
> + return 0;
> +}
> +#endif
> +
> #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
> void __init change_floppy(char *fmt, ...)
> {
> @@ -471,6 +486,16 @@ void __init change_floppy(char *fmt, ...)
>
> void __init mount_root(void)
> {
> +#ifdef CONFIG_ROOT_9P
> + if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR) {
> + if (mount_9p_root())
> + return;
> +
> + printk(KERN_ERR "VFS: Unable to mount root fs via 9p\n");
> +
> + ROOT_DEV = Root_FD0;
> + }
> +#endif
> #ifdef CONFIG_ROOT_NFS
> if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR) {
> if (mount_nfs_root())
> --
> 1.7.1
>
>
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