Improve reverse debugging docs, mention built-in support and supports archs

gdb/doc/ChangeLog:
2019-04-22  Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Reverse Execution): Mention and xref process record
	and replay.  Mention remote and system emulators.
	(Process Record and Replay): List supported architectures.
	Mention that "record btrace" is only supported on Intel
	processors.

2 files changed, 27 insertions, 7 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 6407327..ba15232 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,11 @@
+2019-04-22  Pedro Alves  <palves@redhat.com>
+
+	* gdb.texinfo (Reverse Execution): Mention and xref process record
+	and replay.  Mention remote and system emulators.
+	(Process Record and Replay): List supported architectures.
+	Mention that "record btrace" is only supported on Intel
+	processors.
+
 2019-04-17  Alan Hayward  <alan.hayward@arm.com>
 
 	* gdb.texinfo (Other Command-Line Arguments for gdbserver)
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index a3a5f3e..0733e1a 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -6697,6 +6697,12 @@ assumes that the memory and registers that the target reports are in a
 consistant state, but @value{GDBN} accepts whatever it is given.
 }.
 
+On some platforms, @value{GDBN} has built-in support for reverse
+execution, activated with the @code{record} or @code{record btrace}
+commands.  @xref{Process Record and Replay}.  Some remote targets,
+typically full system emulators, support reverse execution directly
+without requiring any special command.
+
 If you are debugging in a target environment that supports
 reverse execution, @value{GDBN} provides the following commands.
 
@@ -6817,6 +6823,11 @@ replay mode as long as the execution log includes the record for the
 previous instruction; otherwise, it will work in record mode, if the
 platform supports reverse execution, or stop if not.
 
+Currently, process record and replay is supported on ARM, Aarch64,
+Moxie, PowerPC, PowerPC64, S/390, and x86 (i386/amd64) running
+GNU/Linux.  Process record and replay can be used both when native
+debugging, and when remote debugging via @code{gdbserver}.
+
 For architecture environments that support process record and replay,
 @value{GDBN} provides the following commands:
 
@@ -6851,13 +6862,14 @@ replay implementation.  This method allows replaying and reverse
 execution.
 
 @item btrace @var{format}
-Hardware-supported instruction recording.  This method does not record
-data.  Further, the data is collected in a ring buffer so old data will
-be overwritten when the buffer is full.  It allows limited reverse
-execution.  Variables and registers are not available during reverse
-execution.  In remote debugging, recording continues on disconnect.
-Recorded data can be inspected after reconnecting.  The recording may
-be stopped using @code{record stop}.
+Hardware-supported instruction recording, supported on Intel
+processors.  This method does not record data.  Further, the data is
+collected in a ring buffer so old data will be overwritten when the
+buffer is full.  It allows limited reverse execution.  Variables and
+registers are not available during reverse execution.  In remote
+debugging, recording continues on disconnect.  Recorded data can be
+inspected after reconnecting.  The recording may be stopped using
+@code{record stop}.
 
 The recording format can be specified as parameter.  Without a parameter
 the command chooses the recording format.  The following recording