Hi David,
On Tue, Apr 13, 2021 at 07:40:12AM +0000, David Laight wrote:
> From: Mitali Borkar
> > Sent: 12 April 2021 00:09
> >
> > This patch fixes the warning identified by checkpatch.pl by replacing
> > __attribute__aligned(size) with __aligned(size)
> >
> > Signed-off-by: Mitali Borkar <mitaliborkar810@xxxxxxxxx>
> > ---
> > .../staging/media/ipu3/include/intel-ipu3.h | 74 +++++++++----------
> > 1 file changed, 37 insertions(+), 37 deletions(-)
> >
> > diff --git a/drivers/staging/media/ipu3/include/intel-ipu3.h
> > b/drivers/staging/media/ipu3/include/intel-ipu3.h
> > index 589d5ccee3a7..d95ca9ebfafb 100644
> > --- a/drivers/staging/media/ipu3/include/intel-ipu3.h
> > +++ b/drivers/staging/media/ipu3/include/intel-ipu3.h
> > @@ -84,7 +84,7 @@ struct ipu3_uapi_grid_config {
> > */
> > struct ipu3_uapi_awb_raw_buffer {
> > __u8 meta_data[IPU3_UAPI_AWB_MAX_BUFFER_SIZE]
> > - __attribute__((aligned(32)));
> > + __aligned(32);
> > } __packed;
>
> WTF?
>
> It either has 1-byte alignment because it is just __u8,
> 32-byte because of the aligned(32),
> or 1 byte because of the outer packed.
>
> What alignment does this (and all the other) structures
> actually need?
32 as noted above. Here packed makes no difference though.
Some of these structs are used embedded in other structs or alone. I
haven't checked this one.
It's also possible to have __packed and __aligned() conflict (in which case
a decent compiler would give you a warning) --- which does not happen
currently AFAIK.
>
> Specifying 'packed' isn't free.
It may be free if the packed alignment of the fields corresponds to
architecture's packing. Here __aligned() is used to satisfy
hardware alignment requirements and __packed is used to ensure the same
memory layout independently of ABI rules.
--
Regards,
Sakari Ailus
