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Date: Sat, 13 Sep 2008 11:48:50 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [PATCH][RFC][RFT] Let qemu-nbd build on Windows
 and replace QEMU_IMG/QEMU_NBD with QEMU_TOOL
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To: Laurent Vivier <Laurent.Vivier@bull.net>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Anthony Liguori wrote:
> Laurent Vivier wrote:
>> Le vendredi 12 septembre 2008 à 20:05 -0500, Anthony Liguori a écrit :
>>  
>>> This patch attempts to clean up the mess with qemu-nbd in the 
>>> Makefile in order to get it building and working on Windows.  I 
>>> checked block-nbd, qemu-img, and qemu-nbd on Windows and Linux and 
>>> everything seems to work.  However, there were some 
>>> defined(QEMU_IMG) that didn't include defined(QEMU_NBD) that now are 
>>> covered by QEMU_TOOL so I'd like Laurent to look them over and see 
>>> if they were intentional.
>>>     
>>
>> If I remember correctly they were intentional:
>> - some of them because qemu-nbd didn't support windows (but you have
>> corrected this)
>> - others because qemu-img doesn't need to open file with O_DIRECT
>> whereas qemu-nbd must (--nocache option) (and I think you break this)
>>
>> Did you test "qemu-nbd --nocache" ?
>>   
>
> No, but this is why I asked :-)
>
> So this begs the question, why does qemu-nbd need to open files with 
> O_DIRECT and why doesn't qemu-img?
>
> Can we just enable the code in both?

Oh, I see.  It's because we don't have bottom halves with QEMU_TOOL.  
That's easy enough to fix.  I'll update the patch.

Regards,

Anthony Liguori