From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from codeconstruct.com.au (pi.codeconstruct.com.au [203.29.241.158]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CF7F368D47; Tue, 22 Sep 2026 01:23:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.29.241.158 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790040218; cv=none; b=u42Zi3XFtSpUuvXhULY1LKdb5JT7gP9zkQgaa+53n0qM0LYKPG7peRqvykxpHXAv1S6I6BwJ13Gk/Is3iek88gf0kKkCcZEp5iYpoLcTYkLA7QTdOoM2Z3vwiKmyX+EIZWXl8/YOwi15TN7wEXsGgMAXskJ3sE7JBqIkD0Zcono= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790040218; c=relaxed/simple; bh=5BuBZZnK32r8ACboo/WQLjtGC4RMRIxwkfQhR2RTwZ4=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=pvIMk/bd76nZgszmSiEi+PS8G/ghBybJUMK6QFZJ0ENcx0MYW9JKu83dXe7+o3nBLq51s1UwBGxcThwTOr8srilC19C5SYEowX0BDNNICz/cE691k/+ANbuWLf+IECXZ37NTwSw2x33mHqmXTTPK1iIGMVK9GgLXkqC0LN2VLwU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codeconstruct.com.au; spf=pass smtp.mailfrom=codeconstruct.com.au; dkim=pass (2048-bit key) header.d=codeconstruct.com.au header.i=@codeconstruct.com.au header.b=St91aZH0; arc=none smtp.client-ip=203.29.241.158 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codeconstruct.com.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codeconstruct.com.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codeconstruct.com.au header.i=@codeconstruct.com.au header.b="St91aZH0" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codeconstruct.com.au; s=2022a; t=1790040207; bh=5BuBZZnK32r8ACboo/WQLjtGC4RMRIxwkfQhR2RTwZ4=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=St91aZH0l7sHl/hP2szhVQYa+WtEiW58YnWbDwsCnqp4OWBW8RbsgdImRUUYZlcAr yq7q4O0XJ6p3NOBxXBC6p9h3K1DYhVeV/cMhWEYpA5vMH9Pyd1gvKwHvqGuaukFK1+ 6qBuk6zC7mRpfWDhpf4WHQ28sNQnRCq1I/hXqEBTgQLbfn58Xa3WWTRz6/ntcunsGh 0BYxnncZLeNNawRXWaKiK7DuxKY0N+n32HGPH9Wb/n3p/3JKdEz7uM1GAtvTkk5lhj t0jmy3x+CzgIapVlugCHMsHzvdB4yWY+xcYTJakR40Uc2r15JfWwjSyXSiqbtu2dVk JWV+sWcIzwnrA== Received: from [192.168.72.161] (210-10-213-150.per.static-ipl.aapt.com.au [210.10.213.150]) by mail.codeconstruct.com.au (Postfix) with ESMTPSA id C71106BA1E; Tue, 22 Sep 2026 09:23:26 +0800 (AWST) Message-ID: Subject: Re: [PATCH net-next] net: mctp: add MCTP_OPT_ROUTE_SRCADDR getsockopt From: Jeremy Kerr To: Faizan Ali , Matt Johnston Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jakub Kicinski , Paolo Abeni , Eric Dumazet , "David S . Miller" , Simon Horman Date: Tue, 22 Sep 2026 09:23:26 +0800 In-Reply-To: <20260921035118.1649687-1-faizana@nvidia.com> References: <20260921035118.1649687-1-faizana@nvidia.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2-0+deb13u1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi Faizan, > Add a new socket option MCTP_OPT_ROUTE_SRCADDR that allows applications > to query which local EID the kernel would use as the source address > when sending to a given destination EID. >=20 > Applications such as PLDM need to advertise a local EID as the event > receiver address to remote endpoints. Previously this required a manual > multi-step lookup via the mctp tool (route show + addr show). > The kernel routing table is the authoritative > source for this mapping, so expose it directly via a socket option. As I had asked earlier, can you elaborate on why this is needed over choosing any local address? Is there a routing topology where this would not work? I'm not against the idea, we just need a fairly solidy justification for adding user ABI that cannot be changed in future. Cheers, Jeremy