[PATCH] passt.1: Fix description of --mtu option

[PATCH] passt.1: Fix description of --mtu option

[Stefano Brivio]

By default, 65520 bytes are advertised, and zero disables DHCP and
NDP options.

Fixes: ec2b58ea4dc4 ("conf, dhcp, ndp: Fix message about default MTU, make NDP consistent")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 passt.1 | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/passt.1 b/passt.1
index 6136fa5..4c90634 100644
--- a/passt.1
+++ b/passt.1
@@ -135,8 +135,10 @@ background (if configured to do so).
 
 .TP
 .BR \-m ", " \-\-mtu " " \fImtu
-Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5).
-By default, no MTU options will be sent.
+Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value
+disables assignment.
+By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU
+minus the length of a 802.3 header, rounded to 32 bits (IPv4 words).
 
 .TP
 .BR \-a ", " \-\-address " " \fIaddr
-- 
@@ -135,8 +135,10 @@ background (if configured to do so).
 
 .TP
 .BR \-m ", " \-\-mtu " " \fImtu
-Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5).
-By default, no MTU options will be sent.
+Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value
+disables assignment.
+By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU
+minus the length of a 802.3 header, rounded to 32 bits (IPv4 words).
 
 .TP
 .BR \-a ", " \-\-address " " \fIaddr
-- 
2.39.2

Re: [PATCH] passt.1: Fix description of --mtu option

[David Gibson]

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On Wed, Mar 15, 2023 at 10:13:50AM +0100, Stefano Brivio wrote:
> By default, 65520 bytes are advertised, and zero disables DHCP and
> NDP options.
> 
> Fixes: ec2b58ea4dc4 ("conf, dhcp, ndp: Fix message about default MTU, make NDP consistent")
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  passt.1 | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/passt.1 b/passt.1
> index 6136fa5..4c90634 100644
> --- a/passt.1
> +++ b/passt.1
> @@ -135,8 +135,10 @@ background (if configured to do so).
>  
>  .TP
>  .BR \-m ", " \-\-mtu " " \fImtu
> -Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5).
> -By default, no MTU options will be sent.
> +Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value
> +disables assignment.
> +By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU
> +minus the length of a 802.3 header, rounded to 32 bits (IPv4 words).
>  
>  .TP
>  .BR \-a ", " \-\-address " " \fIaddr

-- 
David Gibson			| 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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