Bug#440807: increase CONFIG_SERIAL_8250_NR_UARTS (number of serial ports)

[Lukasz Szybalski <lszybalski@uniqueinsuranceco.com>]

maximilian attems wrote:
> On Tue, Jan 08, 2008 at 02:50:41PM -0600, Lukasz Szybalski wrote:
>   
> > Currently we have 1 serial port on motherboard and 2 port pci card. I 
> > would like to add another 4 port pci card. I am not able to do it 
> > because I get a conflict on ttyS.
> >
> > Since regular pc pci limit is on average 3. the max serial ports I could 
> > install is  3x(6port serial card)  + 1 on mother board.  So Max I could 
> > fit on is 19 if I wanted to. Realistically it would be optimal for me to 
> > have  at least 7 available.
> >
> > Is there some kind of setting that can be changed without recompiling 
> > the  kernel to allow this many serial ports or some kernel header that 
> > would increase the number of available serial ports without much problem?
> >     
>
> $  egrep NR_UARTS /boot/config-2.6.24-rc7-amd64  
> CONFIG_SERIAL_8250_NR_UARTS=16
>
> $  egrep RUNTIME_UARTS /boot/config-2.6.24-rc7-amd64  
> CONFIG_SERIAL_8250_RUNTIME_UARTS=4
>
> This can be overridden with the module parameter "nr_uarts", or
> boot-time parameter 8250.nr_uarts.
>
> up to 16 evidently
>
>   

Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled

I edited /boot/grub/menu.lst and change the following lines by adding 
the 8250.nr_uarts=16 at the end of kernel option.

title Debian GNU/Linux,
kernel 2.6.18-5-686 root (hd0,1)
kernel /boot/vmlinuz-2.6.18-5-686 root=/dev/sda2 ro 8250.nr_uarts=16
initrd /boot/initrd.img-2.6.18-5-686
savedefault

Now I've got:
Serial: 8250/16550 driver $Revision: 1.90 $ 16 ports, IRQ sharing enabled

Just for the my info. Is there a setting I could pass on boot time to 
increase the max number of serial ports and then set my 8250.nr_uarts=16 
to let say 20.

Thanks,
Lucas
ps. I added the info on the process of going from 4 to 16 here:
http://lucasmanual.com/mywiki/FaxServer#head-e5a4f60720205d4c950a7ba608cd73a35c978946