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Re: [Xen-devel] Taken fault at bad CS c000...

  • To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
  • Date: Thu, 15 Feb 2007 08:39:53 +0000
  • Delivery-date: Thu, 15 Feb 2007 00:39:20 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcdPZd1PRiWiMh0hR6eatwo259HKHwAtlXJiACBkQ+AADtw0VQAAZhJgAACD4TM=
  • Thread-topic: [Xen-devel] Taken fault at bad CS c000...

On 15/2/07 08:36, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:

> 2) No permission on I/O ports (0xCF8/0xCFC, 0x20e0, 0x20e4)
> which is weird:
>   Seems that this version of VGA bios will try to scan PCI bus.
> 0x20e0/0x20e4 is the I/O BAR configured for integrated graphics
> controller. However I printed all sys_ioperm, and found that Xorg
> only requests for [0x0-0x3ff],[0x40-0x43],[0x60-0x63]. Then each
> time when above ports are accessed within VM86 mode,
> guest_io_okay will fail since related bitmap bits are all 1s. So I'm
> interested that why X-windows can still work under such case. Do
> you know any path to enable I/O ports specially for VM86 mode?

It may be that the X Server fixes up the faults. I'm pretty sure it can do
various bits of fixup emulation.

 -- Keir

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