Re: [dpdk-dev] [PATCH v4 04/12] raw/ioat: add explicit padding to descriptor struct

[Thomas Monjalon <thomas@monjalon.net>]

04/05/2021 14:04, Bruce Richardson:
> On Mon, May 03, 2021 at 11:20:40PM +0200, Thomas Monjalon wrote:
> > 30/04/2021 17:06, Bruce Richardson:
> > > Add an explicit padding field to the end of the descriptor structure so
> > > that when the batch descriptor is defined on the stack for perform-ops, the
> > > unused space is all zeroed appropriately.
> > > 
> > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > ---
> > > --- a/drivers/raw/ioat/rte_ioat_rawdev_fns.h
> > > +++ b/drivers/raw/ioat/rte_ioat_rawdev_fns.h
> > > -	/* 28 bytes of padding here */
> > > +	uint16_t intr_handle; /* completion interrupt handle */
> > 
> > This is more than padding.
> > Does it deserve its own commit?
> > 
> 
> This field is unused by the driver, since we don't use any interrupts, so I
> consider it as padding in that regard. However, I agree that in reality
> it's not padding, but I think rather than having it's own commit, I can
> just reword the patch commit log to cover it. Something like:
> 
> raw/ioat: expand descriptor struct to full 64 bytes
> 
> Although it's unused by the driver, add the interrupt handle field in the
> descriptor to the descriptor structure for completeness, and explicitly add
> the reserved padding field on the end of the structure too. This means that
> when a descriptor is defined on the stack, or initialized by the compiler,
> the unused/reserved space will be zeroed appropriately.

OK, thanks for adding full explanation in the git history.