From: Olaf Hering <olh@suse.de>
initramfs can not be used in current 2.6 kernels, the files will never be
executed because prepare_namespace doesn't care about them. The only way to
workaround that limitation is a root=0:0 cmdline option to force rootfs as
root filesystem. This will break further booting because rootfs is not the
final root filesystem.
This patch checks for the presence of /init which comes from the cpio archive
(and thats the only way to store files into the rootfs). This binary/script
has to do all the work of prepare_namespace().
free_initmem_on_exec() starts the pipe and calls free_initmem once
run_init_process() succeeds.
---
/dev/null | 0
25-akpm/init/main.c | 35 ++++++++++++++++++++++++++++++++---
2 files changed, 32 insertions(+), 3 deletions(-)
diff -puN init/main.c~initramfs-search-for-init init/main.c
--- 25/init/main.c~initramfs-search-for-init 2004-03-20 11:52:16.892461344 -0800
+++ 25-akpm/init/main.c 2004-03-20 11:52:16.895460888 -0800
@@ -580,6 +580,29 @@ static void run_init_process(char *init_
execve(init_filename, argv_init, envp_init);
}
+static int free_initmem_on_exec_helper(void *data)
+{
+ int *fd = data;
+ char c;
+
+ sys_close(fd[1]);
+ sys_read(fd[0], &c, 1);
+ free_initmem();
+ return 0;
+}
+
+static void free_initmem_on_exec(void)
+{
+ int fd[2];
+
+ do_pipe(fd);
+ kernel_thread(free_initmem_on_exec_helper, &fd, 0);
+
+ sys_dup2(fd[1], 255); /* to get it out of the way */
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ sys_fcntl(255, F_SETFD, 1);
+}
extern void prepare_namespace(void);
static int init(void * unused)
@@ -604,17 +627,23 @@ static int init(void * unused)
sched_init_smp();
do_basic_setup();
- prepare_namespace();
-
/*
* Ok, we have completed the initial bootup, and
* we're essentially up and running. Get rid of the
* initmem segments and start the user-mode stuff..
*/
- free_initmem();
+ free_initmem_on_exec();
unlock_kernel();
system_running = 1;
+ /*
+ * check if there is an early userspace init, if yes
+ * let it do all the things prepare_namespace() would do.
+ */
+ run_init_process("/init");
+
+ prepare_namespace();
+
if (sys_open("/dev/console", O_RDWR, 0) < 0)
printk("Warning: unable to open an initial console.\n");
diff -puN -L trashcan/olaf/linux-2.6.5-rc2/init/main.c /dev/null /dev/null
_