qemu discuss - Jan 2007 - Patch: atapi cd dma problems with Solaris x86 quests

I''ve had a look why the Opensolaris kernel running inside qemu-cvs is
reporting timeout errors when booting from the Solaris Express (x86) CD/DVD,
with the default "atapi-cd-dma-enabled=1" setting.


It seems the problem is that qemu hw/ide.c implements "atapi-cd-dma"
only
for scsi READ commands, and assumes that all other scsi commands transfer
data in PIO mode.

But the Solaris ata (atapi) driver expects that scsi commands like INQUIRY,
MODE SENSE, ... transfer their data using DMA transfers, too.


I''ve experimented with the attached patch; it adds DMA support for
non-READ scsi commands to qemu-cvs.  With this patch installed,
the Solaris Express installer is able to boot from the install media,
and I don''t have to specify "-B atapi-cd-dma-enabled=0" any
more.


With this patch installed, a Windows ME or Windows 2000 qemu guest reports
that it uses DMA with the CD, too.
-------------- next part --------------
Index: hw/ide.c
==================================================================RCS file:
/cvsroot/qemu/qemu/hw/ide.c,v
retrieving revision 1.50
diff -u -B -r1.50 ide.c
--- hw/ide.c	5 Jan 2007 18:58:34 -0000	1.50
+++ hw/ide.c	12 Jan 2007 18:07:42 -0000
@@ -394,6 +395,7 @@
 } PCIIDEState;
 
 static void ide_dma_start(IDEState *s, BlockDriverCompletionFunc *dma_cb);
+static void ide_atapi_cmd_read_dma_cb(void *opaque, int ret);
 
 static void padstr(char *str, const char *src, int len)
 {
@@ -1062,12 +1064,17 @@
     if (size > max_size)
         size = max_size;
     s->lba = -1; /* no sector read */
-    s->packet_transfer_size = size;
+    s->io_buffer_size = s->packet_transfer_size = size;
     s->elementary_transfer_size = 0;
     s->io_buffer_index = 0;
 
-    s->status = READY_STAT;
-    ide_atapi_cmd_reply_end(s);
+    if (s->atapi_dma) {
+    	s->status = READY_STAT | DRQ_STAT;
+	ide_dma_start(s, ide_atapi_cmd_read_dma_cb);
+    } else {
+    	s->status = READY_STAT;
+    	ide_atapi_cmd_reply_end(s);
+    }
 }
 
 /* start a CD-CDROM read command */
@@ -1099,14 +1106,16 @@
     }
 
     if (s->io_buffer_size > 0) {
-        if (s->cd_sector_size == 2352) {
-            n = 1;
-            cd_data_to_raw(s->io_buffer, s->lba);
-        } else {
-            n = s->io_buffer_size >> 11;
-        }
+	if (s->lba != -1) {
+	    if (s->cd_sector_size == 2352) {
+		n = 1;
+		cd_data_to_raw(s->io_buffer, s->lba);
+	    } else {
+		n = s->io_buffer_size >> 11;
+	    }
+	    s->lba += n;
+	}
         s->packet_transfer_size -= s->io_buffer_size;
-        s->lba += n;
         if (dma_buf_rw(bm, 1) == 0)
             goto eot;
     }

> 
> I''ve had a look why the Opensolaris kernel running
> inside qemu-cvs is
> reporting timeout errors when booting from the
> Solaris Express (x86) CD/DVD,
> with the default "atapi-cd-dma-enabled=1" setting.
Booting with Solaris NVb54 from CDROM iso and from
the installed B54, I''m no longer seeing timeouts on the
installed version either.

Nice job

Ben
--
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tested in a Gentoo Linux qemu 0.8.2 host running Solaris 10u3 and NexentaOS
alpha 6 guests
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attached file with the patch in diff format so it can be easier to apply and
test
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> 
> I''ve had a look why the Opensolaris kernel running
> inside qemu-cvs is
> reporting timeout errors when booting from the
> Solaris Express (x86) CD/DVD,
> with the default "atapi-cd-dma-enabled=1" setting.
> 
> 
> It seems the problem is that qemu hw/ide.c implements
> "atapi-cd-dma" only
> for scsi READ commands, and assumes that all other
> scsi commands transfer
> data in PIO mode.
> 
> But the Solaris ata (atapi) driver expects that scsi
> commands like INQUIRY,
> MODE SENSE, ... transfer their data using DMA
> transfers, too.
> 
> 
> I''ve experimented with the attached patch; it adds
> DMA support for
> non-READ scsi commands to qemu-cvs.  With this patch
> installed,
> the Solaris Express installer is able to boot from
> the install media,
> and I don''t have to specify "-B
> atapi-cd-dma-enabled=0" any more.

I can confirm this for your patch merged into qemu_cvs20070120sat on a sparc
HOST with sol-nv-b54-x86-v1.iso as guest.

Awesome, thanks Mr. Keil!

 
 > With this patch installed, a Windows ME or Windows
> 2000 qemu guest reports
> that it uses DMA with the CD, too.
> Index: hw/ide.c

Does SiSoft Sandra also confirm this (not just the ControlPanel)??


-MB
--
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> I can confirm this for your patch merged into
> qemu_cvs20070120sat on a sparc HOST 
I mean, it is already inside cvs, as you had submitted it yesterday.


-MB
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