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

From: Jason Brittain
Subject: Re: [Qemu-devel] enabling bus-master IDE driver
Date: Thu, 11 Nov 2004 11:02:16 -0800
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913

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, 
+                /*bdrv_set_geometry_hint(s->bs, s->cylinders, s->heads, 
             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

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