Re: [PATCH] [gdb/aarch64] pauth: Create new feature string for pauth to prevent crashing older gdb's

[Eli Zaretskii via Gdb-patches <gdb-patches@sourceware.org>]

> Date: Wed, 12 Apr 2023 09:46:31 +0100
> Cc: gdb-patches@sourceware.org, alex.bennee@linaro.org,
>  richard.henderson@linaro.org, peter.maydell@linaro.org
> From: Luis Machado <luis.machado@arm.com>
> 
> How about the following flow?
> 
> In the future the @samp{org.gnu.gdb.aarch64.pauth} feature string might be
> deprecated in favor of feature string @samp{org.gnu.gdb.aarch64.pauth_v2}.
> 
> The @samp{org.gnu.gdb.aarch64.pauth_v2} feature has the exact same contents
> as feature @samp{org.gnu.gdb.aarch64.pauth}.
> 
> Targets reporting Pointer Authentication support via the remote protocol
> should always use the newer feature string
> @samp{org.gnu.gdb.aarch64.pauth_v2}.
> 
> The reason for having feature @samp{org.gnu.gdb.aarch64.pauth_v2} is a bug in
> previous versions of @value{GDBN} (versions 9, 10, 11 and 12).  This bug
> caused @value{GDBN} to crash whenever the target reported support for Pointer
> Authentication (using feature string @samp{org.gnu.gdb.aarch64.pauth}) and also
> reported additional system registers that were not accounted for by
> @value{GDBN}.  This is common when using emulators and on bare-metal debugging
> scenarios.

The flow is OK, but the last paragraph is too long.  The main reason
of this text is to tell people to use the v2 feature, not to explain
why it exists.  So the explanation of the reason should be shorter
like

  We recommend always using the @samp{org.gnu.gdb.aarch64.pauth_v2}
  feature because using @samp{org.gnu.gdb.aarch64.pauth} could crash
  older versions of @value{GDBN} due to a known bug in those versions.

Is it really important to say that the bug happens only when
additional system registers are reported?