qemu-char: Saner naming of memchar stuff & doc fixes

New device, has never been released, so we can still improve things
without worrying about compatibility.

Naming is a mess.  The code calls the device driver CirMemCharDriver,
the public API calls it "memory", "memchardev", or "memchar", and the
special commands are named like "memchar-FOO".  "memory" is a
particularly unfortunate choice, because there's another character
device driver called MemoryDriver.  Moreover, the device's distinctive
property is that it's a ring buffer, not that's in memory.  Therefore:

* Rename CirMemCharDriver to RingBufCharDriver, and call the thing a
  "ringbuf" in the API.

* Rename QMP and HMP commands from memchar-FOO to ringbuf-FOO.

* Rename device parameter from maxcapacity to size (simple words are
  good for you).

* Clearly mark the parameter as optional in documentation.

* Fix error reporting so that chardev-add reports to current monitor,
  not stderr.

* Replace cirmem in C identifiers by ringbuf.

* Rework documentation.  Document the impact of our crappy UTF-8
  handling on reading.

* QMP examples that even work.

I could split this up into multiple commits, but they'd change the
same documentation lines multiple times.  Not worth it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 5 insertions, 8 deletions

diff --git a/qemu-options.hx b/qemu-options.hx
index 2d44137bf9..046bdc0f63 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1736,7 +1736,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
     "-chardev msmouse,id=id[,mux=on|off]\n"
     "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
     "         [,mux=on|off]\n"
-    "-chardev memory,id=id,maxcapacity=maxcapacity\n"
+    "-chardev ringbuf,id=id[,size=size]\n"
     "-chardev file,id=id,path=path[,mux=on|off]\n"
     "-chardev pipe,id=id,path=path[,mux=on|off]\n"
 #ifdef _WIN32
@@ -1778,7 +1778,7 @@ Backend is one of:
 @option{udp},
 @option{msmouse},
 @option{vc},
-@option{memory},
+@option{ringbuf},
 @option{file},
 @option{pipe},
 @option{console},
@@ -1887,13 +1887,10 @@ the console, in pixels.
 @option{cols} and @option{rows} specify that the console be sized to fit a text
 console with the given dimensions.
 
-@item -chardev memory ,id=@var{id} ,maxcapacity=@var{maxcapacity}
+@item -chardev ringbuf ,id=@var{id} [,size=@var{size}]
 
-Create a circular buffer with fixed size indicated by optionally @option{maxcapacity}
-which will be default 64K if it is not given.
-
-@option{maxcapacity} specifies the max capacity of the size of circular buffer
-to create. Should be power of 2.
+Create a ring buffer with fixed size @option{size}.
+@var{size} must be a power of two, and defaults to @code{64K}).
 
 @item -chardev file ,id=@var{id} ,path=@var{path}