[Qemu-devel] Using OHCI to replace UHCI can improve the USB performance dramatically under windows

[Steven Hu]

Hello, all
Is there anyone interested in the performance of USB under QEMU?
I found that when use OHCI to replace UHCI in qemu, it will improve
the performance of USB storage device.  I have tested it, the
performance is almost equal of a real usb device.
The way to do this is making
little change in the file xen-3.1.0-src/tools/ioemu/hw/pc.c .

--- pc.c.original       2007-08-14 14:04:33.000000000 +0800
+++ pc.c        2007-08-08 08:57:33.000000000 +0800
@@ -897,7 +897,9 @@
        pci_piix4_acpi_init(pci_bus, piix3_devfn + 2);

    if (pci_enabled && usb_enabled) {
-        usb_uhci_init(pci_bus, piix3_devfn + (acpi_enabled ? 3 : 2));
+        //usb_uhci_init(pci_bus, piix3_devfn + (acpi_enabled ? 3 : 2));
+               //usb_ohci_init(pci_bus, 3, -1);
+        usb_ohci_init(pci_bus, 3,piix3_devfn + (acpi_enabled ? 3 : 2));
    }

 #ifndef CONFIG_DM


There are some issues forLinux guest OS. I am trying to fix it. Is