Re: [Qemu-devel] enabling bus-master IDE driver

[Jason Brittain]

zitu wrote:
> Quoting James Boddington <address@hidden>:
>
> > James Boddington wrote:
> >
> > > I found 2000 is using pio as well.
> >
> > I'll change that. It is with 2000 + sp4. I am getting pio on the primary
> > ide and dma on the secondary ide channel.
>
> on xp, it's PIO for both. DMA if available only on primary (hdd).
>
> For linux guest, as root, hdparm -d0/-d1 doesn't work.
>
> But with the DMA patch, you should see DMA is on with the following:
> 'hdparm /dev/hda'
> It's also visible in /proc/ide/hda/settings :)

Looks like mine (with the patch) shows DMA is off:

/dev/hda:
 multcount      = 16 (on)
 IO_support     =  0 (default 16-bit)
 unmaskirq      =  0 (off)
 using_dma      =  0 (off)
 keepsettings   =  0 (off)
 readonly       =  0 (off)
 readahead      = 256 (on)
 geometry       = 33288/16/63, sectors = 33554432, start = 0

And, I can set the IO_support to 1 with hdparm -c1 /dev/hda,
but, as you say, I can't set using_dma to 1 with
hdparm -d1 /dev/hda.  So, looks like it's off, and I can't turn
it on.  Should the IO_support = 1 help any with disk performance?
It doesn't appear to.

--
Jason Brittain