On Mon, Jul 31, 2017 at 9:38 PM,  [off-list ref] wrote:

Hi Arnd,

I think you are right, but removing this is maybe the wrong fix.

The issue is, that CAPI messages are packed byte streams and yes the
64bit extension of CAPI is not very good designed for modern CPU
constrains with alignment, since the data pointer for the buffer is not
on a 64bit boundary.

I also attempted to just mark the pointer as __packed, which would address
the warning as well, but then I saw that no code refers to it.

All hardware controller implementations I know do
ignore the data pointer, they are simple awaiting the data of the given
length directly after the message. Only the application interface on 64
bit systems really need the 64 bit data pointer value, which is usually
set in the HW driver to the mapped user space address of the used data
buffer if the user space process is 64bit.
The user space CAPI library correctly use byte stream access functions
to read/write the values. So the correct solution for this driver would
be to use stream access functions as well here and not add a 64 bit
pointer.

I'm not sure what change you are proposing here.

On the other hand I do not think the any people use this driver on 64
bit systems today, because they would run into this issue.

Right. Another way of addressing the warning would be to add a
'depends on BROKEN || !64BIT' dependency in Kconfig, which
would serve to document the fact that it's broken and prevent
us from running into it.

        Arnd