RE: [Xen-devel] Third release of GPL'd PV drivers for Windows

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> James Harper, le Fri 09 Nov 2007 21:37:23 +1100, a écrit :
> > Windows appears to mostly give buffers aligned to a multiple of
> > 512 bytes (sector size) which may allow me to just grant Dom0 access to
> > the page... although what happens to the other bytes in the page?
> 
> They are untouched, so you can make the optimization, unless you are
> paranoid enough about information leakage and don't trust dom0.
> 

I was more thinking along the lines of what happens when I need to grant the 
same page more than once... eg windows request 1 (read) comes along and wants 
to read a sector into offset 1024 in PFN 12345, and while that request is in 
progress, windows request 2 (write) comes along and wants to write a sector 
from offset 1536 in PFN 12345 (eg same PFN). Is anything going to break if I 
grant the same page twice (two separate grant table references but the same 
PFN)? What about if I grant it once as read only and then as read/write (or in 
the other order)?

I'm hopeful that all of those problems have been considered and solved 
previously and that it will 'just work'...

Thanks

James



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