Re: init process freezed after run_init_process

[rjy <rjy@angelltech.com>]

Jan Engelhardt wrote:
>>>Make your own initrd and put a bash into it. Then start that, e.g. (for
>>>our linux live cd), initrd=initrd.sqfs root=/dev/ram0 init=/bin/bash
>>
>>I have tried these kernel parameters:
>>init=/bin/bash
>>init=/linuxrc
>>init=/init
>>init=/sbin/init
>>None works.
> 
> 
> What's the error message?

No error message at all. System seems freezed after spit out this message:
	Freeing unused kernel memory: 136k freed
The console echos the keyboard inputs.

It seems that the init started successfully: I attached the output
of "info threads" and "backtrace" after the system freezing.

I am digging the source these days and try to find out if the init
process has really been started. I found some difference between
the normal init process and the freezed init process:
----------------------------------------------------------------
		| Normal init		| Freezed init
----------------------------------------------------------------
mm->total_vm	| 0x145			| 0x1e
mm->map_count	| 9			| 5
----------------------------------------------------------------

Maybe, init is not loaded completely? Or just loaded an invalid one?
I am trying to dump the text segment at user space 0x08040000 of the
init process. But I have not found the way to find the related kernel 
space address. Any clue? Thanks! :)

> 
> 
>>Also, after some google, I found that the format of initrd has changed.
>>I also tried a new initrd with cpio format. The kernel recognized it:
> 
> 
> cpio initrd's (aka initramfs) are new - the "old style" initrd where you
> `mksquasfs mydir initrd.sqfs` (see above) continues to work, though.
> 
> 
>>After the kernel start, I add breakpoints at cpu_idle and do_schedule.
>>cpu_idle never reached, only do_schedule did. Is that strange?
> 
> 
> Until pid 1 is started, the cpu should never be idle.
> 
> 
> Jan Engelhardt

It seems that the init process is started:
(gdb) info threads
   11 Thread 123 (kseriod)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   10 Thread 9 (aio/0)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   9 Thread 8 (kswapd0)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   8 Thread 7 (pdflush)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   7 Thread 6 (pdflush)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   6 Thread 5 (khelper)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   5 Thread 4 (kblockd/0)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   4 Thread 3 (events/0)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
   3 Thread 2 (ksoftirqd/0)  0xc032d485 in do_schedule () at 
/kernel/via/kgdb/kernel/sched.c:923
* 2 Thread 1 (init)  breakpoint () at /kernel/via/kgdb/kernel/kgdb.c:1212
   1 Thread 32768 (Shadow task 0 for pid 0)  0xc032d485 in do_schedule 
() at /kernel/via/kgdb/kernel/sched.c:923

(gdb) bt
#0  breakpoint () at /kernel/via/kgdb/kernel/kgdb.c:1212
#1  0xc774fec4 in ?? ()
#2  0xc010893b in do_IRQ (regs=
       {ebx = -948641792, ecx = -948577792, edx = -944260388, esi = 0, 
edi = -948641792, ebp = -948633844, eax = -944260388, xds = 123, xes = 
123, orig_eax = -252, eip = -1072517263, xcs = 96, eflags = 646, esp = 
-948633660, xss = -948576428})
     at /kernel/via/kgdb/arch/i386/kernel/irq.c:574
#3  0xc0106888 in common_interrupt ()
#4  0xc01063f6 in do_signal (regs=0xc774e000, oldset=0x0) at 
/kernel/via/kgdb/arch/i386/kernel/signal.c:581
#5  0xc01064d9 in do_notify_resume (regs=0xc774ffc4, oldset=0x0, 
thread_info_flags=1)
     at /kernel/via/kgdb/arch/i386/kernel/signal.c:629