On Thu, Mar 22, 2012 at 01:52:30PM -0700, Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org wrote:

quoted

This can be used to force 32bit alignment in amd64 code in order to match
definitions in 32bit userspace.
For new things it would make sense to force 64bit alignment of 64bit fields
for 32bit code.

o.k. so I'll use aligned attribute to align user-kernel interface
data structure to 8 byte boundary.  That should work for 32-bit and
64-bit user and kernel space and does't hurt performance either?

If the structure is only for user/kernel interfacing then it is much
better to add explicit padding fields to naturally place 64 bit
quantities on an 8 byte alignment than to mess with gcc specific
attributes (user space has a much wide choice of compilers).

This was David's second suggestion. Better to do this now before the
driver is accepted :)

Jason
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