RE: [Xen-ia64-devel] xencons interrupt problem

[Alex Williamson <alex.williamson@xxxxxx>]

On Mon, 2006-06-26 at 11:27 +0800, Tian, Kevin wrote:
> I seem to understand your proposal now. Do you mean that some early 
> table will report the irq line information for the console device out of the 
> ACPI table?

Hi Kevin,

   Yes, the PCDP firmware table tells us all the details of the console
UART, base address, GSI, interrupt polarity/trigger, etc...  So we don't
need any additional ACPI/PCI knowledge to get the UART running in
interrupt mode.

>  If that's the case, I think changes required to achieve this 
> purpose is:
>       1. Modify assign_irq_vector hypercall to allow passing into GSI for 
> check sharing with PCI serial
>               If it's sharing, return existing vector instead of a new 
> allocation
>       2. Add a new flag to indicate such sharing between xen and dom0, 
> and remove checks against this style in all places.
>               When assertion on this irq line happens, pass to xen first and 
> then to dom0

   Great, this is what I was thinking too.  I'll try to look into adding
this.

>       3. Do we need to hide such console from dom0, since the latter 
> only uses para-virtualized xenconsole?

   This is a little tricky.  I think for now we'll likely use the same
CONFIG_XEN_DISABLE_SERIAL option that x86 uses to hide all the UARTs
from dom0.  Ideally we could hide them dynamically to allow a
transparent VP kernel to still use a serial console.  Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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