netdev - RE: [PATCH net-next 8/8] net: phy: use '__packed' instead of '__attribute__((__packed_

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Date:   Mon, 14 Jun 2021 14:28:36 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Weihang Li' <liweihang@...wei.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linuxarm@...wei.com" <linuxarm@...wei.com>,
        Wenpeng Liang <liangwenpeng@...wei.com>
Subject: RE: [PATCH net-next 8/8] net: phy: use '__packed' instead of
 '__attribute__((__packed__))'

From: Weihang Li
> Sent: 11 June 2021 07:37
> 
> Prefer __packed over __attribute__((__packed__)).
> 
> Signed-off-by: Wenpeng Liang <liangwenpeng@...wei.com>
> Signed-off-by: Weihang Li <liweihang@...wei.com>
> ---
>  drivers/net/phy/mscc/mscc_ptp.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/phy/mscc/mscc_ptp.h b/drivers/net/phy/mscc/mscc_ptp.h
> index da34653..01f78b4 100644
...
>  /* Represents an entry in the timestamping FIFO */
>  struct vsc85xx_ts_fifo {
>  	u32 ns;
>  	u64 secs:48;
>  	u8 sig[16];
> -} __attribute__((__packed__));
> +} __packed;

Hmmmm I'd take some convincing that 'u64 secs:48' is anything
other than 'implementation defined'.
So using it to map a hardware structure seems wrong.

If this does map a hardware structure it ought to have
'endianness' annotations.
If it doesn't then why the bitfield and why packed?

	David

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