netdev - Re: [PATCH net-next] net/ncsi: allow to customize BMC MAC Address offset

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Date:   Thu, 8 Aug 2019 04:51:16 +0000
From:   Tao Ren <taoren@...com>
To:     Vijay Khemka <vijaykhemka@...com>,
        Samuel Mendoza-Jonas <sam@...dozajonas.com>,
        "David S . Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        William Kennington <wak@...gle.com>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH net-next] net/ncsi: allow to customize BMC MAC Address
 offset

On 8/7/19 10:36 AM, Vijay Khemka wrote:
> Lgtm except one small comment below.
> 
> On 8/6/19, 5:22 PM, "openbmc on behalf of Tao Ren" <openbmc-bounces+vijaykhemka=fb.com@...ts.ozlabs.org on behalf of taoren@...com> wrote:
> 
>     Currently BMC's MAC address is calculated by adding 1 to NCSI NIC's base
>     MAC address when CONFIG_NCSI_OEM_CMD_GET_MAC option is enabled. The logic
>     doesn't work for platforms with different BMC MAC offset: for example,
>     Facebook Yamp BMC's MAC address is calculated by adding 2 to NIC's base
>     MAC address ("BaseMAC + 1" is reserved for Host use).
>     
>     This patch adds NET_NCSI_MC_MAC_OFFSET config option to customize offset
>     between NIC's Base MAC address and BMC's MAC address. Its default value is
>     set to 1 to avoid breaking existing users.
>     
>     Signed-off-by: Tao Ren <taoren@...com>
>     ---
>      net/ncsi/Kconfig    |  8 ++++++++
>      net/ncsi/ncsi-rsp.c | 15 +++++++++++++--
>      2 files changed, 21 insertions(+), 2 deletions(-)
>     
>     diff --git a/net/ncsi/Kconfig b/net/ncsi/Kconfig
>     index 2f1e5756c03a..be8efe1ed99e 100644
>     --- a/net/ncsi/Kconfig
>     +++ b/net/ncsi/Kconfig
>     @@ -17,3 +17,11 @@ config NCSI_OEM_CMD_GET_MAC
>      	---help---
>      	  This allows to get MAC address from NCSI firmware and set them back to
>      		controller.
>     +config NET_NCSI_MC_MAC_OFFSET
>     +	int
>     +	prompt "Offset of Management Controller's MAC Address"
>     +	depends on NCSI_OEM_CMD_GET_MAC
>     +	default 1
>     +	help
>     +	  This defines the offset between Network Controller's (base) MAC
>     +	  address and Management Controller's MAC address.
>     diff --git a/net/ncsi/ncsi-rsp.c b/net/ncsi/ncsi-rsp.c
>     index 7581bf919885..24a791f9ebf5 100644
>     --- a/net/ncsi/ncsi-rsp.c
>     +++ b/net/ncsi/ncsi-rsp.c
>     @@ -656,6 +656,11 @@ static int ncsi_rsp_handler_oem_bcm_gma(struct ncsi_request *nr)
>      	struct ncsi_rsp_oem_pkt *rsp;
>      	struct sockaddr saddr;
>      	int ret = 0;
>     +#ifdef CONFIG_NET_NCSI_MC_MAC_OFFSET
>     +	int mac_offset = CONFIG_NET_NCSI_MC_MAC_OFFSET;
>     +#else
>     +	int mac_offset = 1;
>     +#endif
>      
>      	/* Get the response header */
>      	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
>     @@ -663,8 +668,14 @@ static int ncsi_rsp_handler_oem_bcm_gma(struct ncsi_request *nr)
>      	saddr.sa_family = ndev->type;
>      	ndev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
>      	memcpy(saddr.sa_data, &rsp->data[BCM_MAC_ADDR_OFFSET], ETH_ALEN);
>     -	/* Increase mac address by 1 for BMC's address */
>     -	eth_addr_inc((u8 *)saddr.sa_data);
>     +
>     +	/* Management Controller's MAC address is calculated by adding
>     +	 * the offset to Network Controller's (base) MAC address.
>     +	 * Note: negative offset is "ignored", and BMC will use the Base
> Just mention negative and zero offset is ignored. As you are ignoring 0 as well.

Thank you Vijay for the review.

Zero offset is not ignored: users get what they want when setting offset to 0 (BMC-MAC = Base-MAC).


Thanks,

Tao