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

[Jason Brittain]

Jens Axboe wrote:
> On Thu, Nov 11 2004, Jason Brittain wrote:
>
> > I just pulled the latest source from CVS (today's), and tried
> > looking at DMA again.
> >
> > Host: Linux 2.6 (Fedora Core 2)
> > Guest: XP corp.
> > It still says the primary IDE channel is in PIO mode, and
> > doesn't seem any faster.
> >
> > Host: Linux 2.6 (Fedora Core 2)
> > Guest: Linux 2.6
> > hdparm now reports that DMA is on for /dev/hda, and I can also
> > turn it on and off.  With it on, it's about twice as fast as
> > it is with it off.  So, this seems to work.
>
>
> If I could install XP, I could take a look. But it will boot for me
> after install, just hangs. If I restart qemu, it complains about a bad
> boot loader.
>
> If I get time I'll look into this.

That's a known problem that aparently still isn't fixed in CVS.
To fix it, apply this patch to your ide.c:

--- hw/ide.c-bad    2004-11-11 07:54:34.000000000 -0800
+++ hw/ide.c   2004-11-11 08:56:23.000000000 -0800
@@ -1895,7 +1895,7 @@
                     s->heads = 16;
                     s->sectors = 63;
                 }
-                bdrv_set_geometry_hint(s->bs, s->cylinders, s->heads, 
s->sectors);
+                /*bdrv_set_geometry_hint(s->bs, s->cylinders, s->heads, 
s->sectors);*/
             }
             if (bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM) {
                 s->is_cdrom = 1;

And, then you must reinstall XP in a new hd image.  Old images
are apparently corrupted, and will not work even with a patched
qemu binary.  I now keep my qemu patched this way and my XP
boots fine.

--
Jason Brittain