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

[Jason Brittain <jason@brittainweb.org>]

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