I got success on my rpi3B terminal, and the following is
my report:

Plan 9 Console
127 holes free
0x0051a000 0x19243000 416452608
416452608 bytes free

Plan 9 from Bell Labs
board rev: 0xa02082 firmware rev: 1574098197
cpu0: 1200MHz ARM Coretex-A53 r0p4
fp: 32 registers, simd
fp: arm arch CFPv3+ with null subarch; rev 4
"l0: 4330: 10Mbps port 0x0 irq -1 ea 000000000000
498M memory: 403M kernel data, 595M user, 3574M swap
cpu1: 1200MHz ARM Coretex-A53 r0p4
cpu2: 1200MHz ARM Coretex-A53 r0p4
cpu3: 1200MHz ARM Coretex-A53 r0p4
ether4330: chip 43430 rev 1 type 1
ether4330: firmware ready
ether4330: addr xxxxxxxxxxxx

/dev/sdM0:	BCM SDHost Controller
/dev/sdM0/data
/dev/sdM0/dos	dos
/dev/sdM0/fs	hjfs
/dev/sdM0/nvram
/dev/sdM0/plan9
bootargs is (tcp, tls, il, local!device) local!/dev/sdM0/fs <====

<now we can login on a rio rc window>
term% aux/wpa -s aterm-dcc371-g -p2 /net/ether0  <====
<now you arer asked as type password>
passwd: xxxxxxxxxxxxx
term% ip/ipconfig -g 192.168.11.1 ether /net/ether0 add 192.168.11.19 255.255.255.0 192.168.11.5 192.168.11.5  <====
term% abaco http://google.co.jp

OK! I got goole.

Problem: I cannot boot this machine from network fs.
My cmdlin.txt is:
console=0 ether0=type=4330 essid=aterm-dcc371-g wpapsk=xxxxxxxxxxxxx wificrypt=wpa2 fs=192.168.11.5 auth=192.168.11.5 bootargs=tls nora6=
However, thos essid etc are not accepted by the booting kernel.

Kenji

PS: 
by the way, I remember someone reported this for arm64, I forgot to archive it, 
please let me know the place