Re: [Qemu-devel] GSoC: Improved image format compatibility

[Lyu Mitnick]

Hello Stefan,

I have spent a whole night to trace the code of block/vpc.c and compare against the VHD specifications

(at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=C2D03242-2FFB-48EF-A211-F0C44741109E&displaylang=en).

It seems that there isn't Fixed hard disk image and Differencing hard disk image support now. I am wondering whether what I has

learned from tracing code is true or false? I also found some possibility of optimization in block/vpc.c. Should I contact mentor 

assigned to this project in private or post the whole idea on the mailing list??

thanks very much

Mitnick

2011/3/30 Stefan Hajnoczi <address@hidden>

On Wed, Mar 30, 2011 at 5:50 AM, Stefan Weil <address@hidden> wrote:
> Am 29.03.2011 23:55, schrieb Lyu Mitnick:
>>
>> Hello all,
>>
>> I have used QEMU to assist me developing embedded system for 3 years. And
>> I
>> want to contribute to QEMU and participate Google Summer of Code this
>> year.
>> I have port binutils so I have some experienced with binary format. I
>> noticed that there is no VHD support in qemu-img. A Virtual Hard Disk(VHD)
>> is a virtual hard disk file format used in Microsoft virtual PC, Hyper-V,
>> virtual box, xVM and Complete PC Backup  of vista and windows 7. I want to
>> add support for VHD in GSoC. I am wondering whether this kind of idea is
>> valuable to QEMU?? Or any another topic related image format is valuable
>> to
>> QEMU??
>>
>> thanks
>>
>> Mitnick
>
> Hello Mitnick,
>
> QEMU (including qemu-img) already supports the format vpc.
> The code in block/vpc.c also uses the name vhd, so I think
> vpc == vhd.

However, it is possible that vpc/vhd has new features that are not yet
supported in QEMU.  There is a listed project idea for updating image
formats on the GSoC wiki page:

http://wiki.qemu.org/Google_Summer_of_Code_2011#Improved_image_format_compatibility

You could assess QEMU's implementation in block/vpc.c and compare
against the latest public file format specification:

http://en.wikipedia.org/wiki/VHD_(file_format)

If you find there are new features or format changes that are not yet
supported in QEMU, this might make a good "Improved image format
compatibility" GSoC project.

Stefan