Re: [Xen-devel] [PATCH v3 1/2] Interface for grant copy operation in libs.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

To unblock Paulina on her series, I would be ok with the cast provided
there is compile-time check to ensure the user-space structure is
identical to the ioctl structure.

That would involve:
1. Introducing BUILD_BUG_ON, offsetof, alignof to libs/ if they are not
   already available.
2. BUILD_BUG_ON(sizeof(A) != sizeof(B))
3. BUILD_BUG_ON(offsetof(A, f1) != offsetof(B, f1)) (enumerate all
   fields)
4. BUILD_BUG_ON(alignof(A) != alignof(B))

Paulina, let me know if you would be interested in doing #1. Normally
this requires reading compiler manuals and some coding. I can give you
more details if you're up for the task, otherwise I will try to find
some time to do it myself.

Wei.

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