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Message-ID: <8eabb29b-7302-d0a2-5949-d7aa6bc59809@linux.intel.com>
Date:   Fri, 9 Sep 2022 15:34:53 +0800
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Subject: Re: [PATCH] net/ncsi: Add Intel OS2BMC OEM command
To:     Paul Fertser <fercerpav@gmail.com>
Cc:     Samuel Mendoza-Jonas <sam@mendozajonas.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <20220909025716.2610386-1-jiaqing.zhao@linux.intel.com>
 <YxrWPfErV7tKRjyQ@home.paul.comp>
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From:   Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
In-Reply-To: <YxrWPfErV7tKRjyQ@home.paul.comp>
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On 2022-09-09 13:59, Paul Fertser wrote:
> Hello,
> 
> On Fri, Sep 09, 2022 at 10:57:17AM +0800, Jiaqing Zhao wrote:
>> The Intel OS2BMC OEM NCSI command is used for controlling whether
>> network traffic between host and sideband is allowed or not. By
>> default such traffic is disallowed, meaning that if the device using
>> NCS (usually BMC) does not have extra active connection, it cannot
>> reach the host.
> 
> Can you please explain the rationale behind introducing this as a
> compile-time kernel config option? I can probably imagine how this can
> make sense as a DT switch (e.g. to describe hardware where there's no
> other communication channel between the host and BMC) but even this
> feels far-fetched.

Previously I submitted a patch to make the NCSI configurable in DT[1], but
it was not accepted by kernel community. A limitation is that currently NCSI
is not a standalone device node, it is controlled by "use-ncsi" option in the
MAC device DT node (like ftgmac100).

Other features like keep phy (also intel-specific oem) also uses kernel option.
(CONFIG_NCSI_OEM_CMD_KEEP_PHY)

[1] https://lore.kernel.org/netdev/20220610165940.2326777-4-jiaqing.zhao@linux.intel.com/T/

> Can you please outline some particular use cases for this feature?
> 
It enables access between host and BMC when BMC shares the network connection
with host using NCSI, like accessing BMC via HTTP or SSH from host.