From: Rob Landley <[email protected]> Make CONFIG_DEVTMPFS_MOUNT apply to initramfs/initmpfs.
Update help text, slightly improve error reporting, move /dev/console open down after devtmpfs mount, don't check IS_ENABLED(CONFIG_TMPFS) before mounting devtmpfs (it's always there, even if just a ramfs alias), and report whether we think we're using tmpfs or ramfs for rootfs. Signed-off-by: Rob Landley <[email protected]> --- drivers/base/Kconfig | 10 ++++++---- drivers/base/devtmpfs.c | 3 ++- init/do_mounts.c | 7 +++---- init/main.c | 17 ++++++++++------- 4 files changed, 21 insertions(+), 16 deletions(-) diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 98504ec..3fb07c1 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -45,16 +45,18 @@ config DEVTMPFS file system will be used instead. config DEVTMPFS_MOUNT - bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs" + bool "Automount devtmpfs at /dev" depends on DEVTMPFS help This will instruct the kernel to automatically mount the devtmpfs filesystem at /dev, directly after the kernel has mounted the root filesystem. The behavior can be overridden with the commandline parameter: devtmpfs.mount=0|1. - This option does not affect initramfs based booting, here - the devtmpfs filesystem always needs to be mounted manually - after the rootfs is mounted. + + In an initramfs based system, this can create the /dev directory + as well. Other root filesystems require a /dev directory to exist + to act as a mount point. + With this option enabled, it allows to bring up a system in rescue mode with init=/bin/sh, even when the /dev directory on the rootfs is completely empty. diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index 44a74cf..eaf8532 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -356,7 +356,8 @@ int devtmpfs_mount(const char *mntdir) err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL); if (err) - printk(KERN_INFO "devtmpfs: error mounting %i\n", err); + printk(KERN_ERR "devtmpfs: error %i mounting on %s\n", + err, mntdir); else printk(KERN_INFO "devtmpfs: mounted\n"); return err; diff --git a/init/do_mounts.c b/init/do_mounts.c index dea5de9..6daf63e 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -599,7 +599,6 @@ void __init prepare_namespace(void) mount_root(); out: - devtmpfs_mount("dev"); sys_mount(".", "/", NULL, MS_MOVE, NULL); sys_chroot("."); } @@ -614,8 +613,9 @@ static struct dentry *rootfs_mount(struct file_system_type *fs_type, if (test_and_set_bit(0, &once)) return ERR_PTR(-ENODEV); - if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs) + if (is_tmpfs) fill = shmem_fill_super; + printk(KERN_INFO "rootfs is %s\n", is_tmpfs ? "tmpfs" : "ramfs"); return mount_nodev(fs_type, flags, data, fill); } @@ -637,9 +637,8 @@ int __init init_rootfs(void) (!root_fs_names || strstr(root_fs_names, "tmpfs"))) { err = shmem_init(); is_tmpfs = true; - } else { + } else err = init_ramfs_fs(); - } if (err) unregister_filesystem(&rootfs_fs_type); diff --git a/init/main.c b/init/main.c index b3c6e36..e6bf551 100644 --- a/init/main.c +++ b/init/main.c @@ -1007,12 +1007,6 @@ static noinline void __init kernel_init_freeable(void) do_basic_setup(); - /* Open the /dev/console on the rootfs, this should never fail */ - if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) - pr_err("Warning: unable to open an initial console.\n"); - - (void) sys_dup(0); - (void) sys_dup(0); /* * check if there is an early userspace init. If yes, let it do all * the work @@ -1024,7 +1018,16 @@ static noinline void __init kernel_init_freeable(void) if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) { ramdisk_execute_command = NULL; prepare_namespace(); - } + } else if (config_enabled(CONFIG_DEVTMPFS_MOUNT)) + sys_mkdir("/dev", 0755); + devtmpfs_mount("dev"); + + /* Open the /dev/console on the rootfs, this should never fail */ + if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) + pr_err("Warning: unable to open an initial console.\n"); + + (void) sys_dup(0); + (void) sys_dup(0); /* * Ok, we have completed the initial bootup, and
