From: David Gibson <david@gibson.dropbear.id.au>
To: Volker Diels-Grabsch <v@njh.eu>
Cc: passt-dev@passt.top
Subject: Re: [PATCH 5/5] Improve clarity of comment
Date: Thu, 18 Sep 2025 12:43:30 +1000 [thread overview]
Message-ID: <aMtx0ibrZlymoN7h@zatzit> (raw)
In-Reply-To: <20250916192209.3986375-6-v@njh.eu>
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On Tue, Sep 16, 2025 at 09:21:16PM +0200, Volker Diels-Grabsch wrote:
> The new wording clarifies that we (1) use the broadcast MAC address
> only until we know the actual MAC address of the guest, and (2) our
> first packets will not necessarily "reach" the guest, in the sense of
> being processed rather than dropped. (Which is why we actively send an
> initial ARP and/or NDP message, to get the guest MAC address as soon
> as possible.)
>
> Signed-off-by: Volker Diels-Grabsch <v@njh.eu>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> tap.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tap.c b/tap.c
> index 0f8ee25..399eeaa 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -1512,9 +1512,9 @@ void tap_backend_init(struct ctx *c)
> case MODE_PASST:
> tap_sock_unix_init(c);
>
> - /* In passt mode, we don't know the guest's MAC address until it
> - * sends us packets. Use the broadcast address so that our
> - * first packets will reach it.
> + /* In passt mode, we don't know the guest's MAC address until
> + * it sends us packets. Until then, use the broadcast address
> + * so that our first packets will have a chance to reach it.
> */
> memcpy(&c->guest_mac, MAC_BROADCAST, sizeof(c->guest_mac));
> break;
> --
> 2.47.3
>
--
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
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next prev parent reply other threads:[~2025-09-18 2:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-16 19:21 [PATCH v6 1/5] Volker Diels-Grabsch
2025-09-16 19:21 ` [PATCH 1/5] Show debug message whenever we observe a new guest MAC address Volker Diels-Grabsch
2025-09-17 5:05 ` David Gibson
2025-09-16 19:21 ` [PATCH 2/5] Introduce constant MAC_BROADCAST Volker Diels-Grabsch
2025-09-17 7:29 ` David Gibson
2025-09-16 19:21 ` [PATCH 3/5] Fix --no-icmp description and make it imply --no-ndp Volker Diels-Grabsch
2025-09-17 7:29 ` David Gibson
2025-09-16 19:21 ` [PATCH 4/5] Send an initial ARP and NDP request to resolve the guest IP address Volker Diels-Grabsch
2025-09-18 2:32 ` David Gibson
2025-09-16 19:21 ` [PATCH 5/5] Improve clarity of comment Volker Diels-Grabsch
2025-09-18 2:43 ` David Gibson [this message]
2025-09-17 14:32 ` [PATCH v6 1/5] Stefano Brivio
2025-09-19 0:59 ` Volker Diels-Grabsch
2025-09-19 1:45 ` David Gibson
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