Commit bbe4b412 authored by Petr Machata's avatar Petr Machata Committed by Jakub Kicinski
Browse files

Documentation: networking: Add a caveat to nexthop_compat_mode sysctl 



net.ipv4.nexthop_compat_mode was added when nexthop objects were added to
provide the view of nexthop objects through the usual lens of the route
UAPI. As nexthop objects evolved, the information provided through this
lens became incomplete. For example, details of resilient nexthop groups
are obviously omitted.

Now that 16-bit nexthop group weights are a thing, the 8-bit UAPI cannot
convey the >8-bit weight accurately. Instead of inventing workarounds for
an obsolete interface, just document the expectations of inaccuracy.

Fixes: b72a6a7a ("net: nexthop: Increase weight to u16")
Signed-off-by: default avatarPetr Machata <petrm@nvidia.com>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/b575e32399ccacd09079b2a218255164535123bd.1733740749.git.petrm@nvidia.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 24c6843b

Documentation/networking/ip-sysctl.rst

+6 −0
Original line number Diff line number Diff line
@@ -2170,6 +2170,12 @@ nexthop_compat_mode - BOOLEAN 
	understands the new API, this sysctl can be disabled to achieve full

	performance benefits of the new API by disabling the nexthop expansion

	and extraneous notifications.



	Note that as a backward-compatible mode, dumping of modern features

	might be incomplete or wrong. For example, resilient groups will not be

	shown as such, but rather as just a list of next hops. Also weights that

	do not fit into 8 bits will show incorrectly.



	Default: true (backward compat mode)



fib_notify_on_flag_change - INTEGER