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Re: problem bring up initramfs and busybox

To: "Florian Fainelli" <florian@openwrt.org>
Subject: Re: problem bring up initramfs and busybox
From: myuboot@fastmail.fm
Date: Tue, 17 Nov 2009 18:58:35 -0600
Cc: "Chris Dearman" <chris@mips.com>, "linux-mips" <linux-mips@linux-mips.org>
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On Wed, 18 Nov 2009 01:39 +0100, "Florian Fainelli"
<florian@openwrt.org> wrote:
> Hi,
> 
> Le mercredi 18 novembre 2009 01:31:33, myuboot@fastmail.fm a écrit :
> > On Tue, 17 Nov 2009 13:54 -0800, "Chris Dearman" <chris@mips.com> wrote:
> > > Kevin D. Kissell wrote:
> > > > This looks like another boot file system setup problem to me.  Are you
> > > > sure that there's an executable init image at /mnt/root/sbin/init?  I'm
> > > > pretty sure that the path that you provide to your new init has to be
> > > > relative to the new root.
> > >
> > > That sounds right.
> > >
> > > Andrew, my suggestion would be to change your initramfs /init script to
> > > invoke "/bin/busybox sh" as the last command instead of "exec
> > > switch_root". The "Kernel panic - not syncing: Attempted to kill init!"
> > > says that switch_root is exiting for some reason. It could be anything
> > > from missing files/devices on the /mnt/root file system to a bug in
> > > busy_box.
> > > By booting into the shell you can run the command by hand (maybe with
> > > strace if you have it) to help identify where the problem is.
> > >
> > > Chris
> > 
> > Chris,
> > 
> > Thanks for your response. Now I changed my init file to the following -
> > #!/bin/busybox sh
> > mount -t proc proc /proc
> > mount -t sysfs sysfs /sys
> > mdev -s
> > /bin/busybox sh
> > 
> > The Kernel panic is gone but the shell still does not come up. Somehow
> > there is no printout on the screen.  Below is the error info.
> > I have tried similar things previously. I also tried using a statically
> > linked hello world in the place of init script. But the result is
> > similar - no print out from either hello world or busybox.
> > [  1.169000] TCP cubic registered
> > [    1.173000] NET: Registered protocol family 17
> > [   15.811000] Freeing unused kernel memory: 1032k freed
> > [   33.978000] Algorithmics/MIPS FPU Emulator v1.5
> > 
> > And here is the trace on BDI -
> > 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 "/bin/busybox",
> > argv=0x4f73dc, envp=0x4f73ec, regs=0x97987f30)
> >     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
> > 
> > Let me provide some history about what I am trying to do here in case it
> > is relevant to the issue. I have a MIPS32 board very similar to AR7.
> > Previously it has working toolchain/u-boot/kernel. I changed the board
> > from little endian to big endian mode and have been trying to upgrade
> > the toolchain/u-boot/kernel (gcc 4.4.1/u-boot2009.08/kernel 2.6.31). I
> > made some changes to the u-boot and kernel on console initialisation in
> > order to bring up the console. Up to the point, the kernel comes up
> > normally.
> > 
> > Since the time I start porting, I have been wondering if any change
> > related to exception needs to be done due to the endianess change. But
> > recently I found an AR7 patch for big endian mode(
> > https://lists.openwrt.org/pipermail/openwrt-devel/2009-May/004262.html)
> > and I did not see any change related to exception there. I hope the
> > issue is not something related to exception that messes up the
> > execution. Sorry if the above is a stupid question. I am trying to learn
> > embedded system. Your suggestion will be appreciated.
> 
> If your board is similar to AR7, then you might need the following patch
> which 
> allows you to cope with the different physical offsets on AR7: 
> http://www.linux-mips.org/archives/linux-mips/2009-06/msg00004.html
> -- 
> Best regards, Florian Fainelli
> Email: florian@openwrt.org
> Web: http://openwrt.org
> IRC: [florian] on irc.freenode.net
> -------------------------------
Actually I already got this patch for the board in little endian mode,
and it is still there for the big endian mode. And this is one of the
place I have been wondering if that needs to be changed for big endian. 

thanks. Andrew

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