Message-Id: <1258492145.12353.1345725383@webmail.messagingengine.com>
From: myuboot@fastmail.fm
To: "Florian Fainelli" <florian@openwrt.org>
Cc: "Ralf Baechle" <ralf@linux-mips.org>, linux-kernel@vger.kernel.org,
       "linux-mips" <linux-mips@linux-mips.org>
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References: <1255735395.30097.1340523469@webmail.messagingengine.com>
 <20091117093330.GA24000@linux-mips.org>
 <1258479580.17116.1345691629@webmail.messagingengine.com>
 <200911171848.44137.florian@openwrt.org>
Subject: Re: problem bring up initramfs and busybox
In-Reply-To: <200911171848.44137.florian@openwrt.org>
Date: Tue, 17 Nov 2009 15:09:05 -0600
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On Tue, 17 Nov 2009 18:48 +0100, "Florian Fainelli"
<florian@openwrt.org> wrote:
> Hi,
> 
> On Tuesday 17 November 2009 18:39:40 myuboot@fastmail.fm wrote:
> > On Tue, 17 Nov 2009 10:33 +0100, "Ralf Baechle" <ralf@linux-mips.org>
> > 
> > wrote:
> > > On Mon, Nov 16, 2009 at 06:21:21PM -0600, myuboot@fastmail.fm wrote:
> > > > I have been struggling to bring up a MIPS 32 board with busybox with or
> > > > without initramfs.
> > > > The kernel stucks there without the shell coming up.
> > > >
> > > > [    1.153000] nf_conntrack version 0.5.0 (1024 buckets, 4096 max)
> > > > [    1.161000] ip_tables: (C) 2000-2006 Netfilter Core Team
> > > > [    1.167000] TCP cubic registered
> > > > [    1.170000] NET: Registered protocol family 17
> > > > [   25.971000] Freeing unused kernel memory: 1032k freed
> > > > [   39.969000] Algorithmics/MIPS FPU Emulator v1.5
> > > >
> > > >
> > > > What I tried here is to use initramfs with statically linked busybox.
> > > > The initramfs seems to be up, and runs the commands in the /init one by
> > > > one, and then it goes to a inifite loop in r4k_wait at
> > > > arch/mips/kernel/genex.S.
> > >
> > > r4k_wait is called by the idle loop.  Which means the kernel has no
> > > process
> > > to run so runs the idle loop.  This might be because there is no other
> > > process left running or because all processes are waiting for I/O for
> > > example.  So it's not uncommon that even busy systems ocasionally briefly
> > > run the idle loop.  In other words, seeing the processor executing
> > > r4k_wait does not necessarily mean something went wrong.  In this case -
> > > also along with the other information you've provieded it's not obvious
> > > what has gone wrong.
> > >
> > >   Ralf
> > 
> > According to an email from Kevin, I added a symbolic link from
> > switch_root to busybox. The switch_root seems to be found now based on
> > the execution sequence, but I got the following error - "Kernel panic -
> > not syncing: Attempted to kill init!". This is the same error when I
> > tried to start the shell without initramfs. Something must be wrong, but
> > I can't quite figure out.
> > 
> > [    9.250000] Freeing unused kernel memory: 1032k freed
> > [   10.463000] Algorithmics/MIPS FPU Emulator v1.5
> > [   41.695000] Kernel panic - not syncing: Attempted to kill init!
> > [   41.701000] Rebooting in 3 seconds.
> > 
> > Thanks for your help. Andrew
> > 
> > (gdb) c
> > Continuing.
> > 
> > Breakpoint 2, do_execve (filename=0x9780a000 "/init", argv=0x943dd2bc,
> > envp=0x943dd230, regs=0x97819e30)
> >     at fs/exec.c:1293
> > 1293            retval = unshare_files(&displaced);
> > (gdb) c
> > Continuing.
> > 
> > Breakpoint 2, do_execve (filename=0x9780a000 "/sbin/switch_root",
> > argv=0x4f7450, envp=0x4f7464, regs=0x97819f30)
> >     at fs/exec.c:1293
> > 1293            retval = unshare_files(&displaced);
> > (gdb) c
> > Continuing.
> 
> If you happen to use uClibc and gcc-4.4.0 or superior, make sure that you
> have 
> that patch applied to uClibc: http://www.mail-
> archive.com/uclibc@uclibc.org/msg04483.html
> --
> WBR, Florian

Yes, I am using uClibc and gcc-4.4.1. So I went ahead and applied the
patch on
./toolchain_build_mips/uClibc-0.9.30.1/libc/sysdeps/linux/mips/bits/syscalls.h.
After that I touched ./toolchain_build_mips/uClibc-0.9.30.1/.configured
and rerun make. But the result is the same - "Kernel panic - not
syncing: Attempted to kill init!". Any of your suggestions will be
welcome. I have tried various things such as changes in init script or
using hello_world as the init, but the result is very similar. Thanks a
lot. Andrew

Breakpoint 1, init_post () at init/main.c:839
839             async_synchronize_full();
(gdb) enable 2
(gdb) c
Continuing.

Breakpoint 2, do_execve (filename=0x9780a000 "/init", argv=0x943dd2bc,
envp=0x943dd230, regs=0x97819e30)
    at fs/exec.c:1293
1293            retval = unshare_files(&displaced);
(gdb) c
Continuing.

Breakpoint 2, do_execve (filename=0x9780a000 "/sbin/busybox",
argv=0x4f7478, envp=0x4f748c, regs=0x97819f30)
    at fs/exec.c:1293
1293            retval = unshare_files(&displaced);
(gdb) c
Continuing.
^C
Program received signal SIGSTOP, Stopped (signal).
r4k_wait () at arch/mips/kernel/genex.S:147
147             jr      ra
Current language:  auto; currently asm
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