[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Adding a ttyS



On Mon, Mar 24, 2008 at 02:11:35PM -0500, Mumia W.. wrote:
> In Etch, /dev is managed by udev which wants to create device nodes on 
> the fly.

this is true for most default installs of etch, but it is not necessary.

When the initrd for the kernel id build with yaird (or one uses a custom
kernel without an initrd), then udev need not be installed (or it might
be still be installed but it need not be started at boot, ot it might
start and be configured in udev.conf to manage a directory different
from /dev). None of my installed machines uses udev to manage /dev/ (and
only very few of them have udev installed)

For the original /dev/ttyS* problem, however, it might be that the
kernel needs a boot parameter (or a parameter for the 8250 module, if a
custom kernel with 8250 as module is used) to be able to see more than 4
ttyS

 grep UARTS /boot/config-`uname -r`
CONFIG_SERIAL_8250_NR_UARTS=4
CONFIG_SERIAL_8250_RUNTIME_UARTS=4

Even a kernel recompile might be needed if the maximum number of kernel
configured uarts is too low, and it might be that the etch defaule
kernel is not suitable.

One can ckeck with 

 grep ttyS /var/log/dmesg

how many ttyS are recognized buy the kernel at boot (or with "dmesg|grep
ttyS" after the modprobe of the 8250 module)

In this moment I do not recall the exact syntax for the parametr, but
a google search about "nr_uarts" might help:

   modinfo 8250|grep -i uarts
parm:           nr_uarts:Maximum number of UARTs supported. (1-4) (uint)

-- 
Chi usa software non libero avvelena anche te. Digli di smettere.
Informatica=arsenico: minime dosi in rari casi patologici, altrimenti letale.
Informatica=bomba: intelligente solo per gli stupidi che ci credono.


Reply to: