Re: [Qemu-devel] Re: DMA with Knoppix and qemu (cvs-version)

[Ben Taylor]

---- "Sven Köhler" <address@hidden> wrote: 
> > i just booted a recent knoppix-cd (4.0.2) and i'm trying to enable DMA,
> > but it won't work!
> > 
> > I started qemu with that command:
> > 
> > qemu -m 256 -cdrom knoppix.iso -boot d
> > 
> > But inside knoppix, a "hdparm -d1 /dev/hdc" won't work:
> >   HDIO_SET_DMA failed: Operation not permitted
> 
> Ah ha! DMA mode work for harrdisks, but not for cdroms.
> 
> Strange - why?

cause the mode bits set for HD DMA weren't set for CDROM.