lkml.org 
[lkml]   [1996]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: serial ports
>> This is not a Linux limitation. It is due to the PC architecture. Some 
>> special "inteligent" cards can achieve this by mean of a special driver.
>> Read the Serial-HOWTO, which stands
>>
>> " The number of serial ports you can use is limited by the number of
>> interrupts (IRQ) and port I/O addresses we have to use. This is not a
>> Linux limitation, but a limitation of the PC bus. Each serial devices
>> must be assigned it's own interrupt and address. A serial device can
>> be a serial port, an internal modem, or a multiport serial board.
>
>But this is not true. There must be another reason why Linux' serial
>driver doesn't allow multiple ports to use the same IRQ. The serial driver
>could very well ask the serial port if it was the one to generate the
>interrupt. Don't tell me it's impossible, I have done it myself. Just
>check base+2 for a zero in bit 0.

>Though, I wouldn't recommend doing so, since it makes the code weird.

Seems this could easily become a big discusion so I desided to add send
along a refferance to the ultimete PC serialport oracle!

Check out:

ftp.phil.uni-sb.de/pub/chris/The_Serial_Port

Or for the Netscape generation:

http://www.colargol.idb.hist.no/~bardj/serial/

It describes the ins and outs of PC serial ports, and also how to hack the
hardware to allow to ports to share an IRQ.

'nuff sayd :)
bardj


\
 
 \ /
  Last update: 2005-03-22 13:38    [W:0.055 / U:0.268 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site