Re: [PATCH] [gdb/doc] There's always a thread

[Pedro Alves <palves@redhat.com>]

On 12/10/2015 04:37 PM, Eli Zaretskii wrote:
>> From: Pedro Alves <palves@redhat.com>
>> Date: Thu, 10 Dec 2015 14:14:59 +0000
>>
>> This warning is a few years out of date -- there's always a thread
>> nowadays.
>>
>> gdb/doc/ChangeLog:
>>
>> 	* gdb.texinfo (Threads): Replace warning with explanation/example
>> 	about single-threaded programs.
> 
> This is OK, but your particular wording makes it sound like systems
> that have no threading libraries at all are not covered by the
> description.  How about not mentioning the threading library and the
> rest of confusing details, and instead just talk about single-threaded
> programs?

Let's try again then.  I was trying to explain things to the
audience that might go

 "OK, but the "single" in single-threaded already
  implies there's one thread.  What about non-threaded programs?
  I mean, those that don't link with -lpthread, even?"

What about this version that follow along your suggestion, but
says "not multi-threaded" instead?

From 18e418498d3199d64d501d1ec92eabec85fb510d Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Thu, 10 Dec 2015 12:54:50 +0000
Subject: [PATCH] [gdb/doc] There's always a thread

This warning is a few years out of date -- there's always a thread
nowadays.

gdb/doc/ChangeLog:

	* gdb.texinfo (Threads): Replace warning with explanation
	about single-threaded programs.
---
 gdb/doc/gdb.texinfo | 22 ++++------------------
 1 file changed, 4 insertions(+), 18 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index e8b419c..bb68e21 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2844,24 +2844,6 @@ the user specify which @code{libthread_db} to use if the default choice
 isn't compatible with the program.
 @end itemize
 
-@quotation
-@emph{Warning:} These facilities are not yet available on every
-@value{GDBN} configuration where the operating system supports threads.
-If your @value{GDBN} does not support threads, these commands have no
-effect.  For example, a system without thread support shows no output
-from @samp{info threads}, and always rejects the @code{thread} command,
-like this:
-
-@smallexample
-(@value{GDBP}) info threads
-(@value{GDBP}) thread 1
-Thread ID 1 not known.  Use the "info threads" command to
-see the IDs of currently known threads.
-@end smallexample
-@c FIXME to implementors: how hard would it be to say "sorry, this GDB
-@c                        doesn't support threads"?
-@end quotation
-
 @cindex focus of debugging
 @cindex current thread
 The @value{GDBN} thread debugging facility allows you to observe all
@@ -2903,6 +2885,10 @@ further qualifier.
 For debugging purposes, @value{GDBN} associates its own thread
 number---always a single integer---with each thread in your program.
 
+From @value{GDBN}'s perspective, a process always has at least one
+thread.  In other words, @value{GDBN} assigns a thread number to the
+program's ``main thread'' even if the program is not multi-threaded.
+
 @table @code
 @kindex info threads
 @item info threads @r{[}@var{id}@dots{}@r{]}
-- 
1.9.3