mwan3 package and MMX_MASK using so many bits

[Philip Prindeville]

> On May 5, 2025, at 11:17 AM, Jonas Lochmann <openwrt at jonaslochmann.de> wrote:
> 
> On Mon, May 05, 2025 at 09:06:02AM -0600, Philip Prindeville via openwrt-devel wrote:
>>> The mask encodes the selected uplink that is used in a policy based
>>> routing. One bit could encode only "no decision" and "uplink 1".
>> 
>> Is that a fixed map?  I.e. (1) there is a max of 6 possible egress paths and
>> (2) any of the other bits could be used without risk of conflict with mwan3?
> 
> That would not work. It is more complicated.
> 
> mwan3 wants at least three bits [1]. Zero is used for "no decision".
> Then a table is generated that maps the used interfaces to numbers [2].
> However, there are three internally used actions (default, blackhole,
> unreachable) that need a number too. They start from the maximum value
> that the bitmask permits. Due to this, theoretically "unused" bits can
> be one or zero depending on internal actions or regular interfaces.
> 
> For the 3 internally actions and "no decision", you already need 2 bits.
> Add at least two uplinks and the third bit is consumed. So running it with
> 3 bits only is possible but adds some limitations (different interfaces
> for IPv6 or more uplinks - you need more bits).
> 
> [1] https://github.com/openwrt/packages/blob/b98fb60/net/mwan3/files/lib/mwan3/common.sh#L124
> [2] https://github.com/openwrt/packages/blob/b98fb60/net/mwan3/files/lib/mwan3/mwan3.sh#L31
> [3] https://github.com/openwrt/packages/blob/b98fb60/net/mwan3/files/lib/mwan3/common.sh#L145


Sorry, are you saying that installing mwan3 precludes any other use of marking bits?