Re: [PATCH] serial/8250: Increase number of serial ports to 32

[Yegor Yefremov <yegor_sub1@visionsystems.de>]

Am 10.11.2010 17:08, schrieb Greg KH:
> On Wed, Nov 10, 2010 at 02:54:39PM +0100, Yegor Yefremov wrote:
>> This will make sure that multiple serial port cards can be
>> used out of the box. Otherwise the user must pass
>> nr_uarts parameter, that will be often forgotten and increases
>> support requests for serial card vendors.
> Has this really happened in the past?

It is still the case. The most requests that we get are "the card doesn't function under Ubuntu...". After examining dmesg one could see that 8250 driver is initialized with 4 UARTS.

There are also lots of questions and bugs concerning this subject. Like this one: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/125524. I even found some entries from 2010:
http://www.gnulinux.in/forum/4-port-serial-card-installation-fedora-11

> What is the downside of changing
> this option that has been around for many years now?  Also note that
> multi-port serial cards are more rare these days than they used to be so
> changing this seems a bit pointless now.

I can say that those cards are still selling. They're not dead.

The downside is that those card are not working out of the box and users not experienced in Linux often miss this parameter. Also some Live Linuxes like Ubuntu (perhaps I missed something) don't provide command line parameter, so you have to reload the driver with proper parameter.

I understand that it is somehow a responsibility of distribution maintainers to properly configure the kernel, but I hope that if vanilla kernel would increase default value, then they will also follow.

Best regards,
Yegor