Re: [Qemu-devel] [PATCH 0/4 V8] char: Add CirMemCharDriver and provide QMP interface

[Lei Li <lilei@linux.vnet.ibm.com>]

Hi Anthony,

As 1.4 freeze is going to close, should this patch series be merged?
It has been on mailing list for a long time after last time
I rebased and fixed the comment from Eric.

On 12/06/2012 10:56 PM, Lei Li wrote:
> This patch series attempts to add new char backend CirMemCharDriver with
> a circular buffer and expose it to users by introducing QMP interface
> memchar-write and memchar-read and via the command line like the other
> CharDriverStates.
>
> Serial ports in qemu always use CharDriverStates as there backends,
> Right now, all of our backends always try to write the data from the
> guest to a socket or file. The concern from OpenStack is that this could
> lead to unbounded disk space usage since they log the serial output.
> For more detail of the background info:
> https://bugs.launchpad.net/nova/+bug/832507
>
> So we want to use a circular buffer in QEMU instead, and then OpenStack
> can periodically read the buffer in QEMU and log it.
>
> The QMP commands introduced like:
>
> { 'command': 'memchar-write',
>    'data': {'chardev': 'str', 'size': 'int', 'data': 'str',
>             'format': 'str' } }
>
> { 'command': 'memchar-read',
>    'data': {'chardev': 'str', 'size': 'int', 'format': 'str' },
>    'returns': 'str' }
>
> Expose CirMemCharDriver via the command line like:
>
> qemu -chardev memory,id=foo,maxcapacity=65536 -serial chardev:foo
>
> Introduce HMP command 'console' like:
>
> (qemu) console foo
> foo: Input data
>
> Note:
> Now all of the feature were implemented, and the pervious comments
> are fixed up too. Since this patch series have been for mailing list
> for some time and missed 1.3, rebase it with minor fix.
>
> Changes since v7:
>    - Rebase the code and fix the format error pointed by Eric.
>    - Modify the version info.
>
> Changes since v6:
>    - Improve the document based on Luiz's comments.
>    - Keep pointing to the right position in cbuf for the case producer
>      and consumer might overflow for long running VMs pointed by Luiz.
>    - Limit the size of read_data to the amount of bytes available in the
>      circular buffer.
>    - Other fixups from Luiz.
>
> Changes since v5:
>    - Avoid writing the IAC information to the queue.
>    - Grammar of the doc for command line options improved from Eric.
>
> Changes since v4:
>    - Get rid of all CongestionControl bits, and assume a dropping behavior
>      based on Luiz's suggestion for now. Will add it when we add async
>      support to QMP.
>    - Squashed the patches about CirMemCharDriver in one.
>    - Other fixups from Luiz.
>
> Changes since v3:
>    - Improve the algorithm of circular buffer based on Anthony's
>      suggestion.
>    - Some changes suggested by Luiz and Blue.
>    - And other fixups.
>
> Changes since v2:
>    - Add congestion mechanism. For the 'block' option as sync command,
>      will support it later when we gain the necessary infrastructure
>      enhancement.
>    - Add HMP 'console' command so that can interact with multiple
>      chardevs via a single monitor socket.
>    - Make the circular buffer backend and the current MemCharDriver
>      live in parallel, expose a new char backend with circular buffer
>      CirMemCharDriver suggested by Luiz.
>    - Other fixs from Eric and Markus.
>
> Changes since v1:
>    - Exposing the MemCharDriver via command line.
>    - Support base64 data format suggested by Anthony and Eric.
>    - Follow the new rule for the name of qmp command from Eric.
>
>
> Lei Li (4):
>    qemu-char: Add new char backend CirMemCharDriver
>    QAPI: Introduce memchar-write QMP command
>    QAPI: Introduce memchar-read QMP command
>    HMP: Introduce console command
>
>   hmp-commands.hx  |   72 +++++++++++++++++++
>   hmp.c            |   99 +++++++++++++++++++++++
>   hmp.h            |    3 +
>   monitor.c        |   15 ++++
>   monitor.h        |    3 +
>   qapi-schema.json |   96 +++++++++++++++++++++++++
>   qemu-char.c      |  217 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   qemu-config.c    |    3 +
>   qemu-options.hx  |   10 +++
>   qmp-commands.hx  |   89 +++++++++++++++++++++
>   10 files changed, 607 insertions(+), 0 deletions(-)
>
>


-- 
Lei