Add an initial script to mount several file systems

kernel/src/fs/rootfs.rs

@@ -7,12 +7,9 @@ use libflate::gzip::Decoder as GZipDecoder;
 use spin::Once;
 
 use super::{
-    cgroupfs::{init as cgroupfs_init, singleton as cgroupfs_singleton},
     fs_resolver::{FsPath, FsResolver},
     path::MountNode,
-    procfs::{self, ProcFS},
     ramfs::RamFS,
-    sysfs::{init as sysfs_init, singleton as sysfs_singleton},
     utils::{FileSystem, InodeMode, InodeType},
 };
 use crate::{fs::path::is_dot, prelude::*};
@@ -108,22 +105,9 @@ pub fn init(initramfs_buf: &[u8]) -> Result<()> {
             }
         }
     }
-    // Mount ProcFS
-    let proc_dentry = fs.lookup(&FsPath::try_from("/proc")?)?;
-    proc_dentry.mount(ProcFS::new())?;
     // Mount DevFS
     let dev_dentry = fs.lookup(&FsPath::try_from("/dev")?)?;
     dev_dentry.mount(RamFS::new())?;
-    // Mount SysFS
-    let sys_dentry = fs.lookup(&FsPath::try_from("/sys")?)?;
-    sysfs_init();
-    let sysfs: Arc<dyn FileSystem> = sysfs_singleton().clone();
-    sys_dentry.mount(sysfs)?;
-    // Mount CgroupFs
-    cgroupfs_init();
-    let cgroup_dentry = fs.lookup(&FsPath::try_from("/sys/fs/cgroup")?)?;
-    let cgroupfs: Arc<dyn FileSystem> = cgroupfs_singleton().clone();
-    cgroup_dentry.mount(cgroupfs)?;
 
     println!("[kernel] rootfs is ready");
     Ok(())

test/src/apps/scripts/init.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# SPDX-License-Identifier: MPL-2.0
+
+# TODO: This script simulates the process of mounting filesystems as performed by 
+# a generic init process. It should later be replaced by the actual init process.
+mount -t sysfs none /sys
+mount -t proc none /proc
+mount -t cgroup2 none /sys/fs/cgroup

test/src/etc/profile

@@ -0,0 +1,6 @@
+# FIXME: Mounting FSes via /etc/profile is fragile (risk of multiple mounts from 
+# login shells). Throw away this operation when we have a proper initial process.
+
+if [ -f /test/init.sh ]; then
+    . /test/init.sh
+fi