Re: [Qemu-devel] [RFC] introduce a dynamic library to expose qemu block API

[Kevin Wolf <kwolf@redhat.com>]

Am 13.07.2012 11:43, schrieb Stefan Hajnoczi:
> On Fri, Jul 13, 2012 at 11:27:55AM +0200, Christoph Hellwig wrote:
>> On Fri, Jul 13, 2012 at 10:13:15AM +0100, Stefan Hajnoczi wrote:
>>> How is that different from all the qemu-io commands?
>>
>> qemu-io has no modes to just dumb the output without additional
>> information / statistics or for the write case just take user input
>> instead of a pattern.  I actually tried to add raw arguments to
>> qemu-io, which still worked ou ok for reads but started to get
>> fairly ugly for the write.
>>
>> What I use in production right now is a trivial qemu-cat tool that
>> just does the raw reads and writes, but I think adding it as a new
>> sub command to qemu-img instead of another tool seems a bit cleaner.
>>
>> If you and Kevin or Anthony disagree and want the qemu-cat tool I can
>> submit a patch for that instead.
> 
> Okay, I see what you mean.  I have used the hex output mode (when you
> use the verbose option) but it's not raw.
> 
> Sounds like you want a qemu-dd :).  I think adding that to qemu-img is
> fine though since it's already the tool that users are familiar with for
> image file manipulation and that gets shipped.

It still feels a bit more like qemu-io-style operations. Not sure what
your use case looks like exactly, but adding a qemu-io command that
reads data from a file and writes it at a given offset into the images
(or vice versa) should be easy. This would be more or less a qemu-dd.

If you need to get data from stdin or output it to stdout, then it might
not be the right solution.

Kevin