Serial console not working after device detection.

Serial console not working after device detection.

[Brice Figureau]

Hi,

On two of my servers (some Dell poweredge 1850 and 2850), booting a 
2.6.26 debian kernel while at the same time looking at the serial 
console, nothing is printed after the following snippet:
...
Linux agpgart interface v0.103
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a NS16550A
????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

The serial port of these servers is configured as 115200n8 and connected 
to an Opengear serial console server for remote administration through ssh.

This is not an issue per-se, but for an unknown reason 2.6.25 and 2.6.26 
debian kernels don't boot succesfully, and I'm trying to understand why, 
which is a complex task when you don't see anything :-)
The latest known debian kernel that boots fine is a 2.6.22 (I didn't try 
2.6.23 or 2.6.24).

On this kernel that boots, the first lines that the serial console 
displays are those from the initrd.

After the boot the dmesg contains the following lines which are just 
after the last line displayed (ie the serial8250: ttyS0 is at... line):

pnp: the driver 'serial' has been registered
pnp: match found with the PnP device '00:06' and the driver 'serial'
00:06: ttyS0 at I/O 0x3f8 (irq = 4) is a NS16550A
pnp: the driver 'parport_pc' has been registered
FDC 0 is a National Semiconductor PC87306
RAMDISK driver initialized: 16 RAM disks of 65536K size 1024 blocksize
...

Is there anything I can do to display something after the device 
detection, in order to understand why those kernels are not booting?

Many thanks for any answer,
Please CC: me on replies, as I'm not subscribed to the list.
--
Brice Figureau

Re: Serial console not working after device detection.

[Alan Cox]

Known problem - compile out the PnP serial support

Re: Serial console not working after device detection.

[Brice Figureau]

On 27/09/08 23:33, Alan Cox wrote:
> Known problem - compile out the PnP serial support

Thanks Alan, that was it.

I recompiled without the pnp serial support and I could finally see the 
messages. Any chance it will get fixed soon?
I had a look to the archives and could only find only a couple of bug 
reports since a few years, so I guess that's not enough pressure for 
anyone to care :-(
I'll file a bugzilla bug report if there is none and a debian bug too, 
that might help :-)

For the short story about my not booting kernels: my issue is related to 
a lilo issue in presence of large initrd or kernels (ie I needed to have 
large-memory set in my lilo conf).

Thanks,
--
Brice Figureau

Re: Serial console not working after device detection.

[Alan Cox]

> I'll file a bugzilla bug report if there is none and a debian bug too, 
> that might help :-)

There is one. You need to file patches not bugs for that.