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From: Andreas Schwab <schwab@suse.de>
To: Jim Blandy <jimb@codesourcery.com>
Cc: Alain Magloire <alain@qnx.com>, gdb@sources.redhat.com
Subject: Re: invoking GDB from FE and signals
References: <3518719F06577C4F85DA618E3C37AB91054A9EFD@nimbus.ott.qnx.com> 	<vt2bqtvl157.fsf@theseus.home.> <20060518172253.GE21003@brasko.net> 	<jebqtvovg2.fsf@sykes.suse.de> <vt2ac9fj682.fsf@theseus.home.>
X-Yow: A KAISER ROLL?!  What good is a Kaiser Roll without a little  COLE SLAW on the SIDE?
Date: Fri, 19 May 2006 00:59:00 -0000
In-Reply-To: <vt2ac9fj682.fsf@theseus.home.> (Jim Blandy's message of "Thu, 18 	May 2006 15:52:45 -0700")
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Jim Blandy <jimb@codesourcery.com> writes:

> Andreas Schwab <schwab@suse.de> writes:
>> Bob Rossi <bob_rossi@cox.net> writes:
>>
>>> I find in emacs:process.c code that they send the SIGINT in different
>>> ways
>>>     /* If possible, send signals to the entire pgrp
>>>        by sending an input character to it.  */
>>>
>>>     /* TERMIOS is the latest and bestest, and seems most likely to
>>>        work.  If the system has it, use it.  */
>>>     case SIGINT:
>>>       sig_char = &t.c_cc[VINTR];
>>>       break;
>>>     ...
>>>     send_process (proc, sig_char, 1, Qnil);
>>
>> This part is only active if SIGNALS_VIA_CHARACTERS is defined.  That is
>> defined mostly for BSD-derived systems, but not, for example, for Linux.
>> The fallback is to send the signal to the foreground process group of the
>> terminal.
>
> Do you know why they prefer that approach on Linux?

According to s/gnu-linux.h:

/* Let's try this out, just in case.
   Nah.  Rik Faith <faith@cs.unc.edu> says it doesn't work well.  */
/* #define SIGNALS_VIA_CHARACTERS */

1993-06-09  Jim Blandy  (jimb@wookumz.gnu.ai.mit.edu)

	* s/linux.h (SIGNALS_VIA_CHARACTERS): Don't #define this.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."