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

-----Original Message-----
From: Jason Gunthorpe [mailto:jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org]
Sent: Friday, March 23, 2012 2:28 AM
To: Pandit, Parav
Cc: David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org; roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org; linux-
rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 2/9] ocrdma: Driver for Emulex OneConnect RDMA
adapter

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

quoted

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 :)

o.k. I'll align them to naturally 8 byte boundary. 

Jason

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