Re: [Xen-ia64-devel] [PATCH][RFC][TAKE4] the P2M/VP patches

[Alex Williamson <alex.williamson@xxxxxx>]

On Wed, 2006-04-12 at 09:01 +0100, Tristan Gingold wrote:

> > Last, the only way to prevent such io access is from guest itself,
> > meant not compiling native drivers in. Or else there's no way for
> > xen to handle it correctly.
> User should disable drivers in domU.  Everybody agree with that!

   I don't.  Xen needs to handle this better.  domU I/O port space
should be mapped to fault on access.  Writes should be dropped and reads
return -1.  This is how a legacy system would behave.  We don't really
care about performance here, I/O port space is already slow, and this is
really only meant to handle startup time probing.  IMHO, it's
unreasonable to ask users to disable all drivers or even try to tell
them what that means.  The Linux/ia64 kernel currently does a pretty
good job of not blindly probing address spaces looking for hardware.  I
think as long as we handle I/O port space reasonably, we'll make the
driver situation in domU more flexible.  Thanks,

        Alex

-- 
Alex Williamson                             HP Linux & Open Source Lab


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