netdev - Re: [net-next PATCH v3] octeon_ep: pack hardware structure

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Date: Wed, 18 Oct 2023 17:06:05 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Shinas Rasheed <srasheed@...vell.com>
Cc: <horms@...nel.org>, <linux-kernel@...r.kernel.org>, <pabeni@...hat.com>,
 <davem@...emloft.net>, <edumazet@...gle.com>, <egallen@...hat.com>,
 <hgani@...vell.com>, <mschmidt@...hat.com>, <netdev@...r.kernel.org>,
 <sedara@...vell.com>, <vburru@...vell.com>, <vimleshk@...vell.com>
Subject: Re: [net-next PATCH v3] octeon_ep: pack hardware structure

On Mon, 16 Oct 2023 02:20:51 -0700 Shinas Rasheed wrote:
> Clean up structure defines related to hardware data to be
> attributed 'packed' in the code, as padding is not allowed
> by hardware.

Looks like the patch was marked as Changes Requested in pw.
I'm guessing it's because we generally discourage __packed.
It's better to add size asserts, e.g.:

static_assert(sizeof(struct octep_oq_desc_hw) == 16);

__packed also implies lack of alignment, which may force compiler 
to generate worse code.