Re: MPC83xx console : no output after handover

Matthew L. Creech wrote:

On Tue, Mar 31, 2009 at 4:45 PM, Gary Thomas [off-list ref] wrote:

quoted

What does your command line (boot args) when it fails?  It should
probably have something like "console=ttyS0,115200" in it.

Yes, that's what I'm using.  It also seems to be the default if none
is supplied.

For the sake of completeness, here's a full dump:

============
Using MPC831x RDB machine description
Linux version 2.6.29 (mlcreech@lap) (gcc version 4.3.2 (Sourcery G++ Lite 4.3-50
) ) #3 PREEMPT Tue Mar 31 15:10:02 EDT 2009
console [udbg0] enabled
setup_arch: bootmem
mpc831x_rdb_setup_arch()
arch: exit
Zone PFN ranges:
  DMA      0x00000000 -> 0x00008000
  Normal   0x00008000 -> 0x00008000
Movable zone start PFN for each node
early_node_map[1] active PFN ranges
    0: 0x00000000 -> 0x00008000
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 32512
Kernel command line: root=/dev/mtdblock1 init=/bin/sh console=ttyS0,115200
IPIC (128 IRQ sources) at fdffd700
PID hash table entries: 512 (order: 9, 2048 bytes)
clocksource: timebase mult[7800001] shift[22] registered
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Memory: 126236k/131072k available (3260k kernel code, 4692k reserved, 136k data,
 98k bss, 160k init)
SLUB: Genslabs=12, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Calibrating delay loop... 66.30 BogoMIPS (lpj=33152)
Mount-cache hash table entries: 512
net_namespace: 708 bytes
NET: Registered protocol family 16

bio: create slab <bio-0> at 0
Freescale Elo / Elo Plus DMA driver
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP reno registered
NET: Registered protocol family 1
WDT driver for MPC8xxx initialized. mode:reset timeout=65535 (32 seconds)
fsl-elo-dma e00082a8.dma: Probe the Freescale DMA driver for fsl,elo-dma control
ler at e00082a8...
fsl-elo-dma e00082a8.dma: #0 (fsl,elo-dma-channel), irq 71
fsl-elo-dma e00082a8.dma: #1 (fsl,elo-dma-channel), irq 71
fsl-elo-dma e00082a8.dma: #2 (fsl,elo-dma-channel), irq 71
fsl-elo-dma e00082a8.dma: #3 (fsl,elo-dma-channel), irq 71
squashfs: version 4.0 (2009/01/31) Phillip Lougher
Registering unionfs 2.5.1 (for 2.6.29-rc2)
yaffs Mar 31 2009 02:31:59 Installing.
msgmni has been set to 246
alg: No test for stdrng (krng)
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered (default)
io scheduler cfq registered
Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO 0xe0004500 (irq = 16) is a 16550A
console handover: boot [udbg0] -> real [ttyS0]
serial8250.0: ttyS1 at MMIO 0xe0004600 (irq = 17) is a 16550A
============

The fact that you get the ttyS1 line printed is interesting.  At
this point, the kernel is switching from raw console I/O (only
suitable for bring-up messages) to the general serial driver
(interrupt driven, etc).  I'm curious about what the ttyS1 driver
is causing to break...

A couple of things you could try:
  * Disable ttyS1 (take it out of your device tree)
  * Look at the console log when this happens.  Look in your system
    map for the symbol '__log_buf', e.g.
       c031ca54 b __log_buf
    This will get stored at physical location '0x31ca54' and will
    often contain data that didn't get a chance to print, for example
    if you have stuck interrupts that prevent the console from working.
    I'd just run it to this point and then examine the memory - either
    using a BDI if one is attached, or press RESET (I hope you have one!)
    and then look using your boot loader (uBoot, RedBoot, ...)



-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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