On 10/05/2009 04:53 PM, Anthony Liguori wrote:
From: Michael S. Tsirkin<mst@xxxxxxxxxx>
Reset BARs and a couple of other registers on bus reset, as per PCI
spec.
This commit breaks Windows XP restart. After a restart Windows switches
from 800x600 cirrus logic vga to 640x480 standard vga. My guess is that
this is due to two mutually-cancelling bugs:
- the bios fails to initialize one of the registers touched below
- qemu sets up that register in the state the Windows expects the bios
to leave it in instead of the on-reset state
Once we perform the reset the register reverts to its correct reset
state, the bios fails to initialize it, and Windows ignores the device.
I reverted this commit from qemu-kvm.git.
diff --git a/hw/pci.c b/hw/pci.c
index 2dd7213..e2f88ff 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -92,7 +92,20 @@ static inline int pci_bar(int reg)
static void pci_device_reset(PCIDevice *dev)
{
+ int r;
+
memset(dev->irq_state, 0, sizeof dev->irq_state);
+ dev->config[PCI_COMMAND]&= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
+ PCI_COMMAND_MASTER);
+ dev->config[PCI_CACHE_LINE_SIZE] = 0x0;
+ dev->config[PCI_INTERRUPT_LINE] = 0x0;
+ for (r = 0; r< PCI_NUM_REGIONS; ++r) {
+ if (!dev->io_regions[r].size) {
+ continue;
+ }
+ pci_set_long(dev->config + pci_bar(r), dev->io_regions[r].type);
+ }
+ pci_update_mappings(dev);
}
static void pci_bus_reset(void *opaque)
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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