On 11/9/18 9:17 AM, Matthew Wilcox wrote:

quoted

But, later versions of the hardware have instructions that don't have
static offsets for the state components (when the XSAVES/XSAVEC
instructions are used).  So, for those, the structure embedding isn't
used at *all* since some state might not be present.

But *when present*, this structure is always aligned on an 8-byte
boundary, right?

There's no guarantee of that.

There is an "aligned" attribute for each XSAVE state component, but I do
not believe it is set for anything yet.