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Old 11-11-2010, 10:50 AM
Bastian Blank
 
Default serial/8250: Increase number of serial ports detected to 32

On Thu, Nov 11, 2010 at 12:22:46PM +0100, Yegor Yefremov wrote:
> our company is developing multi port serial cards among other
> products. The main problem is, when the customers first install this
> devices especially those with 8 ports, they get only few ports
> detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4 (at least
> by Lenny).

SERIAL_8250_NR_UARTS needs to be changed first.

> Serial interface is
> still not dead in spite of new technologies. So this change is really
> needed.

Well, someone could change the 8250 driver to actually allow
adding/removing ports on runtime, like everything else does it,
including the whole bunch of usb-serial drivers. The the time beeing,
there is a parameter nr_uarts.

Bastian

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Old 11-11-2010, 05:06 PM
Leann Ogasawara
 
Default serial/8250: Increase number of serial ports detected to 32

On Thu, 2010-11-11 at 09:18 +0100, Yegor Yefremov wrote:
> Hello,
>
> our company is developing multi port serial cards among other
> products. The main problem is, when the customers first install this
> devices especially those with 8 ports, they get only 2-3 ports
> detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4. There
> are also many such requests all over the net. Serial interface is
> still not dead in spite of new technologies. So this change is really
> needed. I tried to propagate this change to serial tree maintainers,
> but it ended in proposal to change this through Linux distribution
> maintainers. After all they configure the kernels themselves, not
> necessarily using kernel default values. See this thread:
> http://www.spinics.net/lists/linux-serial/msg03020.html
>
> What do you think about this? Should I open a bug request?

Hi Yegor,

Indeed if you could open a bug in Launchpad so that this request can be
tracked that would be great.

Thanks,
Leann


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Old 11-12-2010, 07:47 AM
Andy Whitcroft
 
Default serial/8250: Increase number of serial ports detected to 32

On Thu, Nov 11, 2010 at 09:18:22AM +0100, Yegor Yefremov wrote:
> Hello,
>
> our company is developing multi port serial cards among other
> products. The main problem is, when the customers first install this
> devices especially those with 8 ports, they get only 2-3 ports
> detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4. There
> are also many such requests all over the net. Serial interface is
> still not dead in spite of new technologies. So this change is really
> needed. I tried to propagate this change to serial tree maintainers,
> but it ended in proposal to change this through Linux distribution
> maintainers. After all they configure the kernels themselves, not
> necessarily using kernel default values. See this thread:
> http://www.spinics.net/lists/linux-serial/msg03020.html
>
> What do you think about this? Should I open a bug request?

I would be interested to know if there are any downsides to increasing
this, are static structures sized based on it etc.

A bug is probabally appropriate, please do reply with the number on this
thread so we can find it easily.

-apw

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Old 11-12-2010, 03:11 PM
Yegor Yefremov
 
Default serial/8250: Increase number of serial ports detected to 32

On Fri, Nov 12, 2010 at 9:47 AM, Andy Whitcroft <apw@canonical.com> wrote:
> On Thu, Nov 11, 2010 at 09:18:22AM +0100, Yegor Yefremov wrote:
>> Hello,
>>
>> our company is developing multi port serial cards among other
>> products. The main problem is, when the customers first install this
>> devices especially those with 8 ports, they get only 2-3 ports
>> detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4. There
>> are also many such requests all over the net. Serial interface is
>> still not dead in spite of new technologies. So this change is really
>> needed. I tried to propagate this change to serial tree maintainers,
>> but it ended in proposal to change this through Linux distribution
>> maintainers. After all they configure the kernels themselves, not
>> necessarily using kernel default values. See this thread:
>> http://www.spinics.net/lists/linux-serial/msg03020.html
>>
>> What do you think about this? Should I open a bug request?
>
> I would be interested to know if there are any downsides to increasing
> this, are static structures sized based on it etc.

Actually you have already spent this memory with defining
CONFIG_SERIAL_8250_NR_UARTS = 48. So there is almost no difference.

> A bug is probabally appropriate, please do reply with the number on this
> thread so we can find it easily.

I'll open a bug request next week. As for now see the same bug request
by opensuse: https://bugzilla.novell.com/show_bug.cgi?id=652954.

Yegor

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Old 11-15-2010, 08:31 AM
Uwe Kleine-König
 
Default serial/8250: Increase number of serial ports detected to 32

Hi Bastian,

On Thu, Nov 11, 2010 at 12:50:00PM +0100, Bastian Blank wrote:
> On Thu, Nov 11, 2010 at 12:22:46PM +0100, Yegor Yefremov wrote:
> > our company is developing multi port serial cards among other
> > products. The main problem is, when the customers first install this
> > devices especially those with 8 ports, they get only few ports
> > detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4 (at least
> > by Lenny).
>
> SERIAL_8250_NR_UARTS needs to be changed first.
>
> > Serial interface is
> > still not dead in spite of new technologies. So this change is really
> > needed.
>
> Well, someone could change the 8250 driver to actually allow
> adding/removing ports on runtime, like everything else does it,
> including the whole bunch of usb-serial drivers. The the time beeing,
> there is a parameter nr_uarts.
This popped up recently on linux-arm-kernel ML:

http://thread.gmane.org/gmane.linux.ports.arm.kernel/92400/focus=93334

So it seems there is more general work to do first.
(Note, I don't know the details, I'm just trying to get the right people
in the discussion.)

Best regards
Uwe

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Old 11-15-2010, 08:44 AM
Yegor Yefremov
 
Default serial/8250: Increase number of serial ports detected to 32

On Fri, Nov 12, 2010 at 5:11 PM, Yegor Yefremov
<yegorslists@googlemail.com> wrote:
> On Fri, Nov 12, 2010 at 9:47 AM, Andy Whitcroft <apw@canonical.com> wrote:
>> On Thu, Nov 11, 2010 at 09:18:22AM +0100, Yegor Yefremov wrote:
>>> Hello,
>>>
>>> our company is developing multi port serial cards among other
>>> products. The main problem is, when the customers first install this
>>> devices especially those with 8 ports, they get only 2-3 ports
>>> detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4. There
>>> are also many such requests all over the net. Serial interface is
>>> still not dead in spite of new technologies. So this change is really
>>> needed. I tried to propagate this change to serial tree maintainers,
>>> but it ended in proposal to change this through Linux distribution
>>> maintainers. After all they configure the kernels themselves, not
>>> necessarily using kernel default values. See this thread:
>>> http://www.spinics.net/lists/linux-serial/msg03020.html
>>>
>>> What do you think about this? Should I open a bug request?
>>
>> I would be interested to know if there are any downsides to increasing
>> this, are static structures sized based on it etc.
>
> Actually you have already spent this memory with defining
> CONFIG_SERIAL_8250_NR_UARTS = 48. So there is almost no difference.
>
>> A bug is probabally appropriate, please do reply with the number on this
>> thread so we can find it easily.
>
> I'll open a bug request next week. As for now see the same bug request
> by opensuse: https://bugzilla.novell.com/show_bug.cgi?id=652954.

I've filed a bug:
https://bugs.launchpad.net/ubuntu/+source/linux-meta/+bug/675453

Yegor

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Old 11-15-2010, 09:46 AM
Yegor Yefremov
 
Default serial/8250: Increase number of serial ports detected to 32

2010/11/15 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:
> Hi Bastian,
>
> On Thu, Nov 11, 2010 at 12:50:00PM +0100, Bastian Blank wrote:
>> On Thu, Nov 11, 2010 at 12:22:46PM +0100, Yegor Yefremov wrote:
>> > our company is developing multi port serial cards among other
>> > products. The main problem is, when the customers first install this
>> > devices especially those with 8 ports, they get only few ports
>> > detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4 (at least
>> > by Lenny).
>>
>> SERIAL_8250_NR_UARTS needs to be changed first.
>>
>> > * * * * * * * * * * * * * * * * * * * * * * * * * * Serial interface is
>> > still not dead in spite of new technologies. So this change is really
>> > needed.
>>
>> Well, someone could change the 8250 driver to actually allow
>> adding/removing ports on runtime, like everything else does it,
>> including the whole bunch of usb-serial drivers. The the time beeing,
>> there is a parameter nr_uarts.
> This popped up recently on linux-arm-kernel ML:
>
> * * * *http://thread.gmane.org/gmane.linux.ports.arm.kernel/92400/focus=93334
>
> So it seems there is more general work to do first.
> (Note, I don't know the details, I'm just trying to get the right people
> in the discussion.)

That's really a time to make the allocation dynamic. But for the time
being it won't hurt to increase the number of detected serial cards.
openSUSE has already accepted such approach:
https://bugzilla.novell.com/show_bug.cgi?id=652954.

Regards,
Yegor


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Old 11-15-2010, 09:56 AM
Russell King
 
Default serial/8250: Increase number of serial ports detected to 32

On Mon, Nov 15, 2010 at 10:31:22AM +0100, Uwe Kleine-König wrote:
> Hi Bastian,
>
> On Thu, Nov 11, 2010 at 12:50:00PM +0100, Bastian Blank wrote:
> > On Thu, Nov 11, 2010 at 12:22:46PM +0100, Yegor Yefremov wrote:
> > > our company is developing multi port serial cards among other
> > > products. The main problem is, when the customers first install this
> > > devices especially those with 8 ports, they get only few ports
> > > detected, cause CONFIG_SERIAL_8250_RUNTIME_UARTS is set to 4 (at least
> > > by Lenny).
> >
> > SERIAL_8250_NR_UARTS needs to be changed first.
> >
> > > Serial interface is
> > > still not dead in spite of new technologies. So this change is really
> > > needed.
> >
> > Well, someone could change the 8250 driver to actually allow
> > adding/removing ports on runtime, like everything else does it,
> > including the whole bunch of usb-serial drivers. The the time beeing,
> > there is a parameter nr_uarts.
> This popped up recently on linux-arm-kernel ML:
>
> http://thread.gmane.org/gmane.linux.ports.arm.kernel/92400/focus=93334

The 8250 serial driver can handle up to 64 ports, and used to do so out
of the box.

However, people complained that they only had up to four ports, and
couldn't see the reason for having the ability to have soo many serial
ports, so things got reduced. This is inspite of having the runtime
'nr_uarts' option...

--
Russell King


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