14.05.2020 17:20, Eric Blake wrote:
On 5/14/20 1:45 AM, Vladimir Sementsov-Ogievskiy wrote:
13.05.2020 04:16, Eric Blake wrote:
Include actions for --add, --remove, --clear, --enable, --disable, and
--merge (note that --clear is a bit of fluff, because the same can be
accomplished by removing a bitmap and then adding a new one in its
place, but it matches what QMP commands exist). Listing is omitted,
because it does not require a bitmap name and because it was already
possible with 'qemu-img info'. A single command line can play one or
more bitmap commands in sequence on the same bitmap name (although all
added bitmaps share the same granularity, and and all merged bitmaps
come from the same source file). Merge defaults to other bitmaps in
the primary image, but can also be told to merge bitmaps from a
distinct image.
I'm sorry for asking it only now on v4.. But still. Why do we need it?
Ease of use.
We can instead run qemu binary (or even new qemu-storage-daemon) and just use
existing qmp commands. Is there a real benefit in developing qemu-img,
maintaining two interfaces for the same thing?
If it makes someone's life easier, and is not hard to maintain, then yes. A
command line interface that calls into QMP is not hard to maintain. And _I_
certainly found it easier to write iotests with this patch in place, so it
already has at least one client.
Of-course, just run qmp commands from terminal is a lot less comfortable than
just a qemu img command.. But may be we need some wrapper, which make it simple
to run one qmp command on an image?
It's simple to make a python wrapper working like
qemu-qmp block-dirty-bitmap-add '{node: self, name: bitmap0, persistent: true}'
/path/to/x.qcow2
This _IS_ such a wrapper. The whole point of this patch is that it is now
simpler to run one (or more) QMP command on an offline image from the command
line. Just because I wrote it in C instead of python, and attached it to an
existing tool instead of writing a new tool, doesn't change the fact that it is
just a wrapper around the existing QMP commands.
OK, that's right.
The thing that I didn't like is that we have to make cli-to-qapi interface
mapping by hand. But I see now that interface you implementing is prepared to
make several actions with same bitmap-name, which can't be achieved with some
kind of automatic interface matching anyway, so my proposal don't match your
needs, sorry for my haste)
--
Best regards,
Vladimir
