Re: [PATCH][gdb/doc] Fix to manual for description of remote protocol

[Pedro Alves <pedro@palves.net>]

On 7/21/20 8:14 PM, Reuben Thomas via Gdb-patches wrote:

> ---
>  gdb/ChangeLog       |  5 +++++
>  gdb/doc/gdb.texinfo | 13 +++++++------
>  2 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index fad4608002..f2f9302078 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,8 @@
> +2020-07-21  Reuben Thomas  <rrt@sc3d.org>
> +
> +	* doc/gdb.texinfo: Correct the description of which remote
> +	protocol commands are mandatory for a stub to implement.
> +

Note this should go to the gdb/doc/ChangeLog file instead. 

>  2020-07-20  John Baldwin  <jhb@FreeBSD.org>
>  
>  	* fbsd-tdep.c (fbsd_skip_solib_resolver): New function.
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index a002084d5b..1e72c0ed32 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -39134,12 +39134,13 @@ For any @var{command} not supported by the stub, an empty response
>  protocol.  A newer @value{GDBN} can tell if a packet is supported based
>  on that response.
>  
> -At a minimum, a stub is required to support the @samp{g} and @samp{G}
> -commands for register access, and the @samp{m} and @samp{M} commands
> -for memory access.  Stubs that only control single-threaded targets
> -can implement run control with the @samp{c} (continue), and @samp{s}
> -(step) commands.  Stubs that support multi-threading targets should
> -support the @samp{vCont} command.  All other commands are optional.
> +At a minimum, a stub is required to support the @samp{?} command to tell
> +@value{GDBN} the reason for halting, @samp{g} and @samp{G} commands for
> +register access, and the @samp{m} and @samp{M} commands for memory
> +access.  Stubs that only control single-threaded targets can implement
> +run control with the @samp{c} (continue) command.  Stubs that support
> +multi-threading targets should support the @samp{vCont} command.  All
> +other commands are optional.
>  

I see you're dropping the reference to the s (step) command.
However, either "s" or "vCont;s" _are_ mandatory if the target supports
hardware single-step.  E.g. an x86 stub that doesn't implement
s or vCont;s won't work.  GDB only implements software single-stepping for
architectures that don't do hardware stepping.

The choice of whether to require s is a little more complicated
than that, but I don't think we need to go into too much detail here.

Do you think the version below is clear enough?

From 68e60bc53a040ad2750277aaa5fc7019eb051c22 Mon Sep 17 00:00:00 2001
From: Reuben Thomas <rrt@sc3d.org>
Date: Wed, 22 Jul 2020 14:19:17 +0100
Subject: [PATCH] Correct an error in the remote protocol specification

The list of commands that a stub must implement was wrong.

gdb/ChangeLog:
2020-07-21  Reuben Thomas  <rrt@sc3d.org>

	* gdb.texinfo (Remote Protocol, Overview): Correct the description
	of which remote protocol commands are mandatory for a stub to
	implement.
---
 gdb/doc/gdb.texinfo | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index a002084d5b9..3bd8ddfd624 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -39134,12 +39134,15 @@ For any @var{command} not supported by the stub, an empty response
 protocol.  A newer @value{GDBN} can tell if a packet is supported based
 on that response.
 
-At a minimum, a stub is required to support the @samp{g} and @samp{G}
+At a minimum, a stub is required to support the @samp{?} command to
+tell @value{GDBN} the reason for halting, @samp{g} and @samp{G}
 commands for register access, and the @samp{m} and @samp{M} commands
 for memory access.  Stubs that only control single-threaded targets
-can implement run control with the @samp{c} (continue), and @samp{s}
-(step) commands.  Stubs that support multi-threading targets should
-support the @samp{vCont} command.  All other commands are optional.
+can implement run control with the @samp{c} (continue) command, and if
+the target architecture supports hardware-assisted single-stepping,
+the @samp{s} (step) command.  Stubs that support multi-threading
+targets should support the @samp{vCont} command.  All other commands
+are optional.
 
 @node Packets
 @section Packets

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-- 
2.14.5