Add ro cmdline option in attempt to keep stock kernel from crashing during init

When trying to boot the stock kernel to a Linux distro the stock kernel
seems to crash often during init.. Kexec to a new kernel works OK though.

Having ro in the cmdline seems to make it maybe a little bit less likely
to crash. Who knows, maybe this only happens when using ext4 as rootfs.

For reference, the dmesg says:

[00000000] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT SMP
Modules linked in: kexec arm_kexec board_mapphone_emu_uart
CPU: 0    Tainted: G        W    (3.0.8-g448a95f #1)
PC is at dput+0xe0/0x2fc
LR is at _raw_spin_lock+0x10/0x14
pc : [<c012fc70>]    lr : [<c0615e90>]    psr: 60000013
sp : df865e18  ip : df865e08  fp : df865e54
r10: 00000000  r9 : df4015a4  r8 : 00200200
r7 : 00100100  r6 : 00000000  r5 : c082c0d8  r4 : df401558
r3 : 00000000  r2 : 00000000  r1 : 00000002  r0 : df4015a4
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
...
Backtrace:
[<c012fb90>] (dput+0x0/0x2fc) from [<c01376b0>] (mntput_no_expire+0x224/0x26c)
[<c013748c>] (mntput_no_expire+0x0/0x26c) from [<c0137720>] (mntput+0x28/0x2c)
[<c01376f8>] (mntput+0x0/0x2c) from [<c011bd90>] (fput+0x13c/0x1e8)
[<c011bc54>] (fput+0x0/0x1e8) from [<c0118284>] (filp_close+0x60/0x80)
[<c0118224>] (filp_close+0x0/0x80) from [<c009b348>] (put_files_struct+0xe4/0x108)
 r7:df917da0 r6:df917da8 r5:00000003 r4:00000000
[<c009b264>] (put_files_struct+0x0/0x108) from [<c009b3ac>] (exit_files+0x40/0x44)
[<c009b36c>] (exit_files+0x0/0x44) from [<c009ce98>] (do_exit+0x5fc/0x6e0)
 r7:000000f8 r6:df864000 r5:00000000 r4:df3db360
[<c009c89c>] (do_exit+0x0/0x6e0) from [<c009cfcc>] (do_group_exit+0x50/0xc4)
[<c009cf7c>] (do_group_exit+0x0/0xc4) from [<c009d058>] (sys_exit_group+0x18/0x20)
 r7:000000f8 r6:00000001 r5:401f4c60 r4:00000004
[<c009d040>] (sys_exit_group+0x0/0x20) from [<c0053b00>] (ret_fast_syscall+0x0/0x30)
Code: 0affffd6 e2860014 eb13970f eaffffd3 (e5833000)
Kernel panic - not syncing: Fatal exception

Author: tmlind

utagboot.sh

@@ -6,7 +6,7 @@
 # Using "noinitrd" does not seem to work here, use bogus initrd instead
 
 default_cmdline="initrd=0x8000000,128K console=ttyO2,115200 fbcon=rotate:1 \
-root=/dev/mmcblk1p23 rootwait init=/sbin/init"
+root=/dev/mmcblk1p23 rootwait ro init=/sbin/init"
 
 target="utags.bin"