Re: [PATCH 2/9] ocrdma: Driver for Emulex OneConnect RDMA adapter

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

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

> > 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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