>Must this be that way ? Is there any hidden mistake of mine or using
>independent IRQ's is the ONLY way out ?
I use a boca research 6-port card and share irqs with no problem. My kernel
build includes CONFIG_SERIAL_SHARE_IRQ and CONFIG_SERIAL_MANY_PORT.
Here's the relevant portion of the /usr/src/linux/Documentation/Configure.help
which is where the prompts come from when you do a make menuconfig (or xconfig
or config).
Extended dumb serial driver options
CONFIG_SERIAL_EXTENDED
If you wish to use any non-standard features of the standard "dumb"
driver, say Y here. This includes HUB6 support, shared serial
interrupts, special multiport support, support for more than the
four COM 1/2/3/4 boards, etc.
Note that the answer to this question won't directly affect the
kernel: saying N will just cause this configure script to skip all
the questions about serial driver options. If unsure, say N.
Support more than 4 serial ports
CONFIG_SERIAL_MANY_PORTS
Say Y here if you have dumb serial boards other than the four
standard COM 1/2/3/4 ports. This may happen if you have an AST
FourPort, Accent Async, Boca (read the Boca mini-HOWTO, available
via FTP (user: anonymous) from
ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/mini), or other custom
serial port hardware which acts similar to standard serial port
hardware. If you only use the standard COM 1/2/3/4 ports, you can
say N here to save some memory. You can also say Y if you have an
"intelligent" multiport card such as Cyclades, Digiboards, etc.
Support for sharing serial interrupts
CONFIG_SERIAL_SHARE_IRQ
Some serial boards have hardware support which allows multiple dumb
serial ports on the same board to share a single IRQ. To enable
support for this in the serial driver, say Y here.
----------------
The boca qualifies as a "dumb" multiport card. It's just a bunch of 16550's
with a limited set of selectable port addresses and IRQ's.
You can tell what options your pre-built kernel has by looking for this
in the /var/log/messages:
Jan 28 17:55:23 curta kernel: Serial driver version 4.27 with MANY_PORTS SHARE_I
RQ enabled
73 de Alan N2YGK
PS: I am running kernel 2.2.0 and have been doing the share irq stuff since
2.1.42 when I got the boca board. I don't know if the 2.0 series has
this support but I think it does and I believe the standard distro kernels
*do not* have this enabled so you will need to build a custom kernel.
