From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202508 header.b=pbzvw4YS; dkim-atps=neutral Received: from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 7F8AC5A0275 for ; Mon, 29 Sep 2025 06:08:39 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202508; t=1759118915; bh=YQXt8bHCxs/cToe9ZcPi9uOdZOKuFA8si/Kk1htbi3g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pbzvw4YSO4GWTNJjEiYRzPqvqKgb4VCTaSr9drk+RKDSseKW3ewViwmqpfHrmUdRf 3J4BL+Vf251F5TrnWAs1LtZ19hlaCPuLHA9JGJTAmrwNp3Ix3H99/mgztuUOPKFf8q q1YuwUNIvvGIJl4uXKaymjX2WK8a6rWmq7C1dOOolb8Y0PMKbkLpmnRjM1KlbAxrcN /0HS/5XlKKgbmVLeTNi8/VrRM5uZcjeeGklvZmllh1pbHOFww0tlo+CQLM5C1arLXP UAUWZCnYO8S0mBfq0R+iTMrrNMuS/CDxKPHkFtm+CTUD2QIz0rdm0T+k3pJLjfSjeF b6AnEL+VdRVqA== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4cZnjv246hz4wDC; Mon, 29 Sep 2025 14:08:35 +1000 (AEST) Date: Mon, 29 Sep 2025 14:04:02 +1000 From: David Gibson To: Jon Maloy Subject: Re: [PATCH v9 9/9] arp/ndp: send gratuitous ARP / unsolicitated NA when MAC cache entry added Message-ID: References: <20250924011330.1168921-1-jmaloy@redhat.com> <20250924011330.1168921-10-jmaloy@redhat.com> <5dda48fc-d854-436d-acd1-734d461efd59@redhat.com> <68dc6be3-9dad-422f-8c4f-ab5bdb580b5b@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="AZyJv2br8l59jH9U" Content-Disposition: inline In-Reply-To: <68dc6be3-9dad-422f-8c4f-ab5bdb580b5b@redhat.com> Message-ID-Hash: BWZA5XFR4SIOYIATRF5NI6VEPWSVFVWR X-Message-ID-Hash: BWZA5XFR4SIOYIATRF5NI6VEPWSVFVWR X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: sbrivio@redhat.com, dgibson@redhat.com, passt-dev@passt.top X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --AZyJv2br8l59jH9U Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 26, 2025 at 07:05:56PM -0400, Jon Maloy wrote: >=20 >=20 > On 2025-09-25 20:55, David Gibson wrote: > > On Thu, Sep 25, 2025 at 09:14:42AM -0400, Jon Maloy wrote: > > >=20 > > >=20 > > > On 2025-09-25 02:36, David Gibson wrote: > > > > On Wed, Sep 24, 2025 at 06:18:52PM -0400, Jon Maloy wrote: > > > > >=20 > > > [...] > > > > >=20 > > > > > I experimented a bit with this. My test program is a simple UDP > > > > > client-server pair, exchanging first 3 UDP messages client->serve= r, followed > > > > > by > > > > > 3 messages server->client. > > > >=20 > > > > With the client on the guest, and server outside? How is the outsi= de > > > > machine arranged - is it a physically separate host? A bridged VM or > > > > container on the same host? Something else? > > >=20 > > > It is a physically separate host. > > >=20 > > > >=20 > > > > > First, I changed the main() loop a bit, so that netlink events are > > > > > handled before all other events, if any. (Basically, I added > > > > > an extra loop before the main loop, only handling netlink events,= before > > > > > moving on to the main loop (where netlink events had been exclude= d.) > > > > > This should secure absolute priority of netlink events before any= other > > > > > events. As you will see below, this made no difference to the sce= narios > > > > > I describe. > > > >=20 > > > > Drat. > > > > > 1: When starting the container, I notice that there is no subscri= ption > > > > > event in PASTA, even though I can see the entry for the remo= te host > > > > > is present in the host's ARP table. There is never any event= coming > > > > > up even if I wait for 10+ minutes. > > > >=20 > > > > Huh.... do we need to do something to ensure we get events for > > > > existing entries in the host ARP table, not just ones that are added > > > > or updated after we're running? > > >=20 > > > It doesn't seem to be possible, >=20 > It actually *is* possible, and I just implemented it. It doesn't solve all > problems, but makes a huge difference. I will add it in v10. Hooray! I thought there ought to be a way. --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --AZyJv2br8l59jH9U Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmjaBTIACgkQzQJF27ox 2Gd6vg//Vru/oXMCjUFIhmAJFNsA/NgYjzu8aCERX93jNEK9VGpg2iHaVqQN3ZH1 uA3wVBcOJVjZcHr2a6BbnWarw8Y+eWo9cn3SULIKWSYuGWdcDbAuAXQNdUT1WvJf mDr9kVWYhjHL9g8nPMEowN9uIrrJoEuRiTts8VCvecGIKvcQrwNV/cUcWzVSkhGF UkiNbeDzvPddmrYNiC8bC3gHl/mqQs48Mqkjks2DJcdXk8hkzCzS6IFkdMYb+WhC BxhGtVACuHuGZmaW8qgeehtSPI/xLUivYzuHNiF60nd0Ie7+FVVzVoNCfLRYlHuU FCY+pvbtpxJAnXWuESyrlotWD8a1xk/5xPwlNqkDK+8VazTkfjWVT+DIcV1hE1yS R4JfKn7eM6BkekiW74i35W4Sk6RdvoyIa/U4lWqkxJsRHIZIt5B6al5k81wsmSn9 Z3yzWaMK/nwlpdxoD2wpXQxsZQhJNn2GlYprM1urzE9ackPzXLD8NBh3kOef0Wii Kb1A08CoL5Aliz7QROAk6Z+8bzz9IdaUXkGrg7xhFC4iljZBIql5CJNMZZt8dI2K fub+SeFNZ20AJkm+JlsTaPZ/0+ceHCOmpAroRobyye6IINVO7kMlECJd+J2IdgWW vdww9VwfoJsfW33BqRMWMMvXikoCmvwoR4970ZGAyYCPBPhxGLk= =JqOZ -----END PGP SIGNATURE----- --AZyJv2br8l59jH9U--