にゅーステレオ天国 (SBCについての記事)

hostapd) setup WiFi access point with Raspberry-Pi OS

Shimoda — Thu, 14 Aug 2025 02:00:00 GMT

install the required packages

apt install -y hostapd

create the hostapd settings

interface = wlan0
...

unblock the WiFi interface with rfkill

we need unblocking the WiFi interface before run hostapd. there are several ways to unblock the WiFi interface. I choose the unblock script for 8812au.

there is a sample script to unblock, save it into /root/unblock-rtl8812au.sh::

#! /bin/bash
find_tgt=/sys/class/net/wlan*
find_opt="-q 8812au"

function find_8812au_dev() {
    for i in $find_tgt; do
        if udevadm info -a --path=$i | grep $find_opt; then
            udevadm info -a --path=$i | sed -n 's/[ \t]*KERNEL=="\(.*\)"/\1/p'
            return 0
        fi
    done
    return 1
}


function find_phy_name() {
    n="$(iw dev $1 info | sed -n 's/[ \t]\+wiphy[ \t]\+\([0-9]\+\)/\1/p')"
    wiphy="Wiphy phy$n"
    iw list | grep -e '^\S' | while read l; do
        #cho "$l - $n - $wiphy"
        if [[ "$l" = $wiphy ]]; then
            echo "phy$n"
            return 0
        fi
    done
    return 1
}


function find_rfkill_id() {
    tmp=$(rfkill list | grep $1 | cut -d " " -f 1)
    echo ${tmp%%:}
}


function unblock() {
    sleep 10
    dev=$(find_8812au_dev)
    echo "got device: $dev"
    phy=$(find_phy_name $dev)
    echo "got phy: $phy"
    id=$(find_rfkill_id $phy)
    rfkill unblock $id
}

unblock

modify the systemd settings

to enable the unblock interface, I use the systemd service settings ExecStartPre.

edit the hostapd.conf directly, copy to the new service, or make the override settings by systemctl edit hostapd.service.

[Service]
...
ExecStartPre=/root/unblock-rtl8812au.sh

start and check the service

after modify the settings for systemd, run and confirm the access point service.

systemctl daemon-reload
systemctl start hostapd
systemctl status hostapd

then enable the service:

systemctl enable hostapd

hostapd) tunning the WiFi access point to speed up

Shimoda — Thu, 14 Aug 2025 02:00:00 GMT

Improve the WiFi access speed.

tuning the hostapd.conf to make it from 8Mbps to 60Mbps in my case.

check WiFi interface capability

iw list to get the capability, my USB WiFi results::

$ iw list
...
     Band 1:
         Capabilities: 0x1962
             HT20/HT40
             Static SM Power Save
             RX HT20 SGI
             RX HT40 SGI
             RX STBC 1-stream
             Max AMSDU length: 7935 bytes
             DSSS/CCK HT40
...
     Band 2:
         Capabilities: 0x862
             HT20/HT40
             Static SM Power Save
             RX HT20 SGI
             RX HT40 SGI
             No RX STBC
             Max AMSDU length: 7935 bytes
             No DSSS/CCK HT40
...
         VHT Capabilities (0x03c031a2):
             Max MPDU length: 11454
             Supported Channel Width: neither 160 nor 80+80
             short GI (80 MHz)
             TX STBC
             SU Beamformee
             +HTC-VHT

modify the hostapd.conf

enable enhanced capabilities by ht_capab or vht_capab in hostapd.conf, almost items disabled by defaults.

I can't find the ht_capab options manual, so cut and try will be needed.

```text# interface=wlan0 interface=wlan0 bridge=br0 driver=nl80211

ctrl_interface=/var/run/hostapd ctrl_interface_group=0

ssid=samplesample macaddr_acl=0

country_code=JP ieee80211d=1

hw_mode=a channel=36

auth_algs=1 wpa=2 wpa_psk=1234567890abcdef1234567890abcdef1234567890123456789abcdef1234567 wpa_key_mgmt=WPA-PSK wpa_pairwise=CCMP

wmm_enabled=1 ieee80211w=0 ieee80211ac=1 ieee80211n=1

ht_capab=[HT20-][HT40+][SHORT-GI-20][SHORT-GI-40][DSSS_CCK-40][MAX-AMSDU-7935] vht_capab=[SHORT-GI-80][TX-STBC-1][+HTC-VHT][MAX-AMSDU-11454] ```

improve for 2.4GHz access point ... failed

I can't get the faster WiFi speed for hw_mode=g as 2.4GHz settings.

ht_capab makes few effects to WiFi speed.

setup the RTL8812AU driver with Raspberry-Pi OS kernel 6.12

Shimoda — Thu, 14 Aug 2025 02:00:00 GMT

This is an experience to build the RTL8812AU driver in Raspberry-Pi OS at 2025/07.

get 8812au driver from github

$ git clone https://github.com/morrownr/8812au-20210820

build

$ sudo apt install -y build-essential
$ sudo apt install -y dkms
$ sudo apt install -y bc
$ cd 8812au-20210820
$ make build

install and use the driver

run the script install-driver.sh to install the modules. the install-driver.sh will also set the modprobe settings.

$ sudo bash install-driver.sh
$ modprobe rtl8812au
$ ip addr
...
wlan1   # <- 8812au

error at build

In my case, Errors were shown in make.log

undefined kasan_hw_tag_enabled

recent Raspberry-Pi OS enable the KASAN but the kernel header package is corrupted. (?)

to fix it, edit the headers to fit the kernel status.

edit the kasan-enable.h in kernel-common/include/linux/kasan.h

static inline bool kasan_hw_tags_enabled(void) {
    return true;
}

WiFi Error or stall after several hours

use the broadcom driver clone: https://github.com/morrownr/8812au-20210820 .

I met the WiFi errors `` after several hours from boot with the community driver https://github.com/lwfinger/rtw88 .

kasan.hの現象は、kernel-header展開中に
overlayfs適用してしまっておかしくなった？

apply overlayfs several directories.

Shimoda — Thu, 31 Jul 2025 00:00:00 GMT

how to reduce the access to SD card in Raspberry-Pi OS.

the one method for it, use the overlay filesystem to several paths in SD card.

here is the script sample to mount the overlayfs onto SD card root file system::

mount-overlay-usr-src: /usr/src/f_overlay
mount-overlay-var-log: /var/log/f_overlay

/usr/src/f_overlay: d:=/mnt/storage1/usr-src
/usr/src/f_overlay: l:=lowerdir=/usr/src
/usr/src/f_overlay: u:=$d/usr-src-upper
/usr/src/f_overlay: w:=$d/usr-src-temp
/usr/src/f_overlay:
    mkdir -p $u $w
    mount -t overlay overlay -o $l,upperdir=$u,workdir=$w $(dir $@)
    touch $@

/var/log/f_overlay: d:=/mnt/storage1/var-log
/var/log/f_overlay: l:=lowerdir=/var/log
/var/log/f_overlay: u:=$d/var-log-upper
/var/log/f_overlay: w:=$d/var-log-temp
/var/log/f_overlay:
    mkdir -p $t $w
    mount -t overlay overlay -o $l,upperdir=$u,workdir=$w $(dir $@)
    touch $@

write down above text to Makefile then run them by::

$ make mount-overlay-usr-src
$ make mount-overlay-var-log

make it to the systemd unit file for persistence mount.

create /etc/systemd/system/mount-overlay.service::

$ cat > /etc/systemd/system/mount-overlay.service <<EOF
[Unit]
Description = mount overlay filesystem to reduce SD card access.
After = mnt-storage1.mount

[Mount]
ExecStart = make -C /path/to/script mount-overlay-var-log
ExecStop = umount -f /var/log

[Install]
WantedBy = default.target
EOF

$ systemctl daemon-reload
$ systemctl start mount-overlay
$ systemctl enable mount-overlay

ARM SBC: install mqtt server with rootless podman

Shimoda — Sun, 22 Jun 2025 23:00:00 GMT

install MQTT server to SBC.

at this time, this MQTT server does not encrypt the communications. we need the TLS encryption for it.

make the configuration file::

cat >> mqtt.conf <<EOF
allow_anonymous false
listener 1883
listener 9001
protocol websockets
persistence true
password_file        /srv/mqtt/mqtt.pwfile
persistence_file     mqtt.db
persistence_location /srv/mqtt/data/

user root  # for podman rootless
EOF

points:
- persistence_file is the relative path from `persistence_location`
- a rootless podman needs `root user` as the running user,
    containers `mqtt` user does not have any permissions to mounted points.

create the container file::

```bash
mkdir app.mqtt; cd app.mqtt
cat > Containerfile <<EOF
FROM debian:12.11-slim

RUN apt update -y
RUN apt install -y mosquitte

RUN mkdir -p /srv/mqtt
RUN mosquitte_passwd -c -b /root/mqtt.pwfile admin ??????
RUN mosquitte_passwd    -b /root/mqtt.pwfile sensor1 ?????
RUN mosquitte_passwd    -b /root/mqtt.pwfile sensor2 ?????
RUN mosquitte_passwd    -b /root/mqtt.pwfile viewer  ?????

COPY mqtt.conf /srv/mqtt/mqtt.conf
CMD ["mosquitte", "-c", "/srv/mqtt/mqtt.conf"]
EOF

build the container::

podman build -t mqtt-server

up the container::

ext=/mnt/external/mqtt
podman run -v /srv/mqtt/data:$ext/data \
           -v /srv/mqtt/log:$ext/log \
           -p 1883 -p 9001 \
           -d mqtt-server

ARM SBC: podman install

Shimoda — Sun, 15 Jun 2025 23:00:00 GMT

My experience in the debian armhf. To install podman, according to https://wiki.debian.org/Podman.

it is need to enable the registory at search::

sudo apt install podman
echo 'unqualified-search-registries=["quay.io"]' > /tmp/registries.conf
CONTAINERS_REGISTRIES_CONF=/tmp/registries.conf podman search podman

move cache directory to an external drive,

sudo mkdir -o /nmt/external/containers.$USER
sudo chown $USER:$USER /nmt/external/containers.$USER
sudo mount -o bind /mnt/external/containers.$USER ~/.local/share/containers

thanks podman github .

I want to build the application from a debian image.

podman pull debian:12.11-slim

build the application.

mkdir app; cd app
echo "FROM debian:12.11-slim" > Containerfile
podman build

install the network program:

sudo apt install uidmap
sudo apt install slirp4netns

thanks github issue .

then run the container:

podman run

ARM SBC: overlayfs error -2

Shimoda — Sat, 14 Jun 2025 23:00:00 GMT

overlayfs errors had began from 2025/05/25, since the SBC was launched at 2024/09/23::

zram-config stop 2025-02-25-08:00:44-JST
ztab remove log /zram1 /var/log /opt/zram/log.bind
serviceConfiguration: Stopping services that interfere with zram device configuration.
removeZdir: Beginning removal of device /dev/zram1.
umount: /var/log (overlay1) unmounted
mergeOverlay: Beginning merge of /opt/zram/opt/zram/log.bind.
ls: /opt/zram/zram1/upper: Input/output error
/opt/zram:
ls: /opt/zram/zram1: Input/output error

I think, it is worth to use overlayfs and zram-config at the sametime, then the overlayfs cannot mount at boot::

kernel: overlayfs: "xino" feature enabled using 2 upper inode
kernel: overlayfs: failed to verify origin (/, ino=12,
kernel: overlayfs: failed to verify upper root origin

to fix it, disable the features of overlayfs at mount. by::

index=off,metacopy=off

here is my fstab.

overlay /var/log overlay noauto,index=off,metacopy=off,workdir=/mnt/external/var-log.tmp,lowerdir=/var/log,upperdir=/mnt/external/var-log 0 0

thanks for arch linux BBS

overlayfsにエラー発生して、以後書き込みができなくなっていた。

その後、再起動してもマウントできなくなった。

あまり起こらないエラーのようで
対処法がなかった。

上のようにすると回避はできた。

何の機能でどういうメリットがあるのかは
調べていないが...

ARM SBC: セットアップ

Shimoda — Wed, 06 Nov 2024 00:00:00 GMT

整備していく

[x] hardware: new USB-hub
[x] hardware: new MCU Board to USB
[x] hardware: MCU Board - センサ等を接続
[x] hardware: mSATA SSD - USB
[x] hardware: MCU Board - USB
[x] hardware: 電源ケーブルの整理 - USB-HubとSBC電源を分岐
[x] hardware: SSD thermal pad, heat sink
5Vの電源を細工するのは多いですね。
ACアダプタ増やすより分岐ケーブル作る方がスッキリするので
mSATAのアダプタがなかったので購入。
動かしたけどすごく熱を持つ...
MCUとセンサの接続は、本数が多くて大変だった。
外れないようにケーブルにホットボンドとかした。(久々...)

ソフト面も整備していく

[x] setup nim
[x] setup dnsmasq - 自宅内のDNS(サブ)
[x] setup ntp - systemd-timesyncd はじめて
[x] config custom - register to systemctl
[x] program: loop / daemon
[ ] program:

確認もいろいろ

[x] watt ... Normal+WiFi 4.5-5.0W
[x] watt ... WiFi+Ether 5.5W
[x] watt ... WiFi+Ether+MCU+Fan 5.9W
[ ] watt ... Normal ?
[ ] SD speed ...
[x] SSD speed ... 30MB/sec

SSD speed

hdparm で確認したSSD読込み速度。
前回とほとんど同じ。
ほとんどUSBの速度で決まってそう。

$ sudo hdparm -Tt /dev/sda1

/dev/sda1:
 Timing cached reads:   684 MB in  2.00 seconds = 341.64 MB/sec
 Timing buffered disk reads:  92 MB in  3.02 seconds =  30.45 MB/sec
shinji@tvbox:/home/root$ sudo hdparm -Tt /dev/sda1

/dev/sda1:
 Timing cached reads:   690 MB in  2.00 seconds = 344.97 MB/sec
 Timing buffered disk reads:  92 MB in  3.01 seconds =  30.53 MB/sec
shinji@tvbox:/home/root$ sudo hdparm -Tt /dev/sda1

/dev/sda1:
 Timing cached reads:   662 MB in  2.01 seconds = 330.05 MB/sec
 Timing buffered disk reads:  92 MB in  3.01 seconds =  30.59 MB/sec

ARM SBC: 再始動

Shimoda — Fri, 06 Sep 2024 09:00:00 GMT

家にまだ稼働していないSBCがあるので
常時稼働のNASを復活させる計画をする。

残念ながらGPIOがないタイプ ... 小型のマイコンボードでカバーする
SSDがつけられない ... USB接続で我慢する(基板だったけど接続は同じだし...)

やることは下のような感じ

筐体を作成する
- SSDがぶらぶらするのを固定
- マイコンボードがぶらぶらのを固定
- Fanありにする
マイコンボードでいろいろ作成する
- 温度センサと接続(工作)
- USB-SerialでSBCに結果を送信
- USB-SerialでSBCからFanスピードを受診してFanを回す
SBCの調整
- USB-Serialで温度を取得・保存
- Fan制御
- LED制御
- SW状態の取得、電源終了などの動作
- これらをserverプログラムにする
  - 制御温度→Fanは、定期的に実行する
  - swの取得→イベント発生
  - LED制御も定期的に実行する
  - LED制御の変更をsocket等で受け付ける

arm-box: RaspberryPi-3B (5台目)

Shimoda — Thu, 05 Sep 2024 04:00:00 GMT

2018/01/20 購入
NAS+Voice kitとして活躍

CPU	BCM2837 1.2GHz
Mem	1GB
Storage	4GB SD card
Keyboard	なし
Mouse	なし
Weight	???g
Monitor	なし
Battery	なし
I/F 1	USB x4
I/F 2	Ethernet 1000M
OS	Raspibian
value	4,839

続きを読む… (残りを読むのに必要な時間は1分)