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

[Anthony Liguori]

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?

Regards,

Anthony Liguori

> > Basically, there are no longer qemu-nbd-*.o objects.  qemu-img-*.o have 
> > -DQEMU_TOOL defined and qemu-img/qemu-nbd use identical copies of those 
> > objects.  A special object is no longer build for nbd.c either.
> >
> > My longer goal would be to eliminate as many qemu-img-* objects as 
> > possible but let's take that one step at a time.
> >     
>
> I think it's a good idea...
>
> Regards,
> Laurent
>