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Why does serial.c not allow you to share the serial console port inter

To: linux-mips@linux-mips.org
Subject: Why does serial.c not allow you to share the serial console port interrupt?
From: Stephens Tim-MGI1634 <Tim.Stephens@motorola.com>
Date: Fri, 23 Apr 2004 09:04:02 -0700
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
Hello,

I'm trying to understand why the serial.c driver does not allow the sharing of 
the serial console interrupt.  There are several places on the net the mention 
you cannot share the console interrupt, however there is no explaination why.  
I assume it has something to do with OOPS reporting.  Please advise.

I'm trying to enable the second serial port on a MIPS based embedded system.  
Both serial ports (16550 type) are attached to the same MIPS interrupt.  The 
console is attached to ttyS0, which shares the MIPS interrupt with ttyS1.

The code in question is:

#ifdef CONFIG_SERIAL_CONSOLE
    /*
     *    The interrupt of the serial console port
     *    can't be shared.
     */
    if (sercons.flags & CON_CONSDEV) {
        for(i = 0; i < NR_PORTS; i++)
            if (i != sercons.index &&
                rs_table[i].irq == rs_table[sercons.index].irq)
                rs_table[i].irq = 0;
    }
#endif

If I change the #ifdef to #if 0 both the console and ttyS1 seem to work ok.

Thanks,
Tim

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