Sorry, I went cross-eyed looking at setsockopt\getsockopt. Both the
new code and old code do not allow it if the socket is connected, but
the Bluetooth spec does it looks. Is the only option on receiving an
MTU REQ to drop the connection and re-open with a lower MTU?
It looks like this in an hcidump, what I am referring to. That MTU is
lower than the default of 672. The spec says not dealing with it
could lead to problems. Could the MTU specifically be allowed to be
set on an open socket to no ill effect in the kernel?
< HCI Command: LE Create Connection (0x08|0x000d) plen 25
bdaddr 00:0B:57:7F:72:BF type 0
interval 96 window 96 initiator_filter 0
own_bdaddr_type 0 min_interval 24 max_interval 40
latency 0 supervision_to 42 min_ce 0 max_ce 0
> HCI Event: Command Status (0x0f) plen 4
LE Create Connection (0x08|0x000d) status 0x00 ncmd 1
> HCI Event: LE Meta Event (0x3e) plen 19
LE Connection Complete
status 0x00 handle 74, role master
bdaddr 00:0B:57:7F:72:BF (Public)
> ACL data: handle 74 flags 0x02 dlen 7
ATT: MTU req (0x02)
client rx mtu 247
