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Re: [Xen-devel] [PATCH] xen/include: public: Document the padding in struct xen_hvm_param

Hi Jan,

On 06/02/2020 15:52, Jan Beulich wrote:
On 06.02.2020 16:41, Julien Grall wrote:
From: Julien Grall <jgrall@xxxxxxxxxx>

There is an implicit padding of 2 bytes in struct xen_hvm_param between
the field domid and index. Make it explicit by introduce a padding
field. This can also serve as documentation.

Note that I don't think we can mandate it to be zero because a guest may
not have initialized the padding.

Agreed - we can mandate such only at introduction, not at any
later time.

Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Thank you!

(I doubt this is the only missing field to make padding explicit.)

Probably not, sadly. I stumbled accross the HVM param implicit padding while looking at liveupdating the HVM param.

I guess I could use pahole to check the paddings are explicit for all the public structure.


Julien Grall

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