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[Xen-devel] Re: user/hypervisor address space solution

On 13 Feb 2006, at 22:56, Hollis Blanchard wrote:

There are very few uses of get/put_user() in common code right now, and
those can be trivially converted. However, there are some in arch code
e.g. xen/arch/x86/domain.c) that cannot, and so the current put_user
interface would need to be preserved as some arch-specific macro. In
this case I'd call it "x86_put_user" to emphasize that only x86 arch
code should be using it. Too many x86isms creep into places like

I expect copy_to/from_user would also need to change. There are places where an array of structs are passed to a hcall, a pointer into that array is passed around in Xen, and individual array entries are copied in/out.

However, this approach seems little different on the Xen side from the xencomm allocator approach -- the pointers are still opaque handles from the p.o.v. of generic Xen code. So some interface changes would be required even if we went down that road.

This opacity should probably be represented in the public header file definitions and in the prototypes of uaccess functions, instead of pretending the handles are really 'foo *' pointers. That would help clean up all uses of the uaccess functions in Xen.

We'll have to see how this all pans out....

 -- Keir

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