[Qemu-devel] Re: [PATCH][RFC][RFT] Let qemu-nbd build on Windows and replace QEMU_IMG/QEMU_NBD with QEMU_TOOL

[Anthony Liguori]

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