Re: [Xen-devel] IOMMU: improve the FLR logic and move it fromhypervisor to Control Panel?

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 20/6/08 06:45, "Yosuke Iwamatsu" <y-iwamatsu@xxxxxxxxxxxxx> wrote:

> Cui, Dexuan wrote:
>> Thanks for the comments.
>> qemu-dm is Device Model. I think Control Panel means Xend/libxc (and other
>> necessary scripts).
>> I think pciback of Dom0 may be not the best place. Beside the drawback you
>> mentioned, for the "Secondary Bus Reset", pciback doesn't own the bridge.
>> In Control Panel, Python script can access PCI config space easily via the
>> sys filesystem.
> 
> I vaguely feel uneasy about allowing python scripts to write in PCI
> config space directly. Is it a common way?

It has the benefit of being easy and flexible and not needing much
re-architecting of the code. pciback would be indeed be a sensible place for
this functionality, and in general a good place for all guest PCI config
space accesses to pass through (whether HVM or PV). It gives us more
consistency in implementation between PV and HVM, and it is a more stable,
stateful and controlled environment than any user-space daemon, let alone a
Python script!

But personally I'm happy doing it in userspace for now at least.

 -- Keir



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