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Message-ID: <2e81babf-2a69-4b41-9b34-6e8ed742b2c1@gmail.com>
Date: Sat, 20 Apr 2024 10:00:54 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: renjun wang <renjunw0@...mail.com>, andrew@...n.ch, linux@...linux.org.uk
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: update fields of mii_ioctl_data for
transferring C45 data.
On 20.04.2024 02:41, renjun wang wrote:
> The phy_id is used as u32 type in function mdio_phy_id_is_c45()
> with the 30th bit for distinguishing C22 and C45. The reg_num is
> also used as u32 type in function mdiobus_c45_read() or someplace
> else. For more C45 information needed and data structure alignment
> consideration, change these two fields to __u32 type which can make
What do you mean with alignment consideration?
> user space program transferring clause 45 type information to kernel
> directly.
>
With this change you break userspace. And in general: If you make
such a change, you should also use it.
> Signed-off-by: renjun wang <renjunw0@...mail.com>
> ---
> include/uapi/linux/mii.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/mii.h b/include/uapi/linux/mii.h
> index 39f7c44baf53..68c085b049de 100644
> --- a/include/uapi/linux/mii.h
> +++ b/include/uapi/linux/mii.h
> @@ -176,8 +176,8 @@
>
> /* This structure is used in all SIOCxMIIxxx ioctl calls */
> struct mii_ioctl_data {
> - __u16 phy_id;
> - __u16 reg_num;
> + __u32 phy_id;
> + __u32 reg_num;
> __u16 val_in;
> __u16 val_out;
> };
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