OpenWRT Boot Times Affected by WiFi: Difference between revisions

wiki.TerraBase.info
Jump to navigation Jump to search
← Older edit
VisualWikitext
mNo edit summary
mNo edit summary
 
(2 intermediate revisions by the same user not shown)
Line 1: Line 1:
== OpenWRT Wireless Regulatory Flags ==
...wondering about long boot times for OpenWRT 25.x.y on a WRT32X or similar if a WiFi Channel is set to "Auto"?


OpenWRT uses the Linux wireless regulatory database to decide which channels, channel widths, and transmit powers are allowed for a selected country code.
Could it really be the fault of a WiFi setting causing long boot times?  Believe it or not: YES!


A regulatory rule has this general form:
=== This Needs to be Done on a Full Linux System with Make, Python, etc. ===
wget <nowiki>https://www.kernel.org/pub/software/network/wireless-regdb/wireless-regdb-2026.03.18.tar.xz</nowiki>


<pre>
Then; tar -xf wireless-regdb-2026.03.18.tar.xz
(frequency_start - frequency_end @ maximum_channel_width), (maximum_power), optional_flags
</pre>


Example:
Go into the directory: cd wireless-regdb-2026.03.18


<pre>
Edit the db.txt File (ORIGINAL "US Section" is below);<pre>
(5250 - 5350 @ 80), (24), DFS, AUTO-BW
</pre>
 
In that example:
 
* <code>5250 - 5350</code> is the allowed frequency range in MHz.
* <code>@ 80</code> means the maximum allowed channel width is 80 MHz.
* <code>(24)</code> means the maximum transmit power is 24 dBm.
* <code>DFS</code> means Dynamic Frequency Selection is required.
* <code>AUTO-BW</code> affects how the regulatory code handles bandwidth across adjacent ranges.
 
=== Flag Meanings ===
 
<code>DFS</code> means Dynamic Frequency Selection. The radio must check for radar before using that channel as an access point. This can delay wireless startup.
 
<code>AUTO-BW</code> means automatic bandwidth handling inside the regulatory code. It helps determine whether wider channels are allowed across compatible frequency ranges. It does not mean automatic channel selection.
 
<code>NO-OUTDOOR</code> means outdoor use is not allowed for that frequency range.
 
<code>NO-IR</code> means No Initiating Radiation. The device is not allowed to initiate transmissions on that range. In practice, this can prevent access point mode or active scanning.
 
<code>NO-OFDM</code> means Orthogonal Frequency-Division Multiplexing is not allowed. This is mostly relevant to special legacy restrictions.
 
<code>wmmrule=ETSI</code> applies ETSI Wireless Multimedia parameters. This affects Quality of Service / contention behavior, not DFS startup delay.
 
=== Practical Effect ===
 
These flags do affect final wireless behavior. They can determine whether OpenWRT, the kernel, the wireless driver, and hostapd allow a radio to start on a given channel.
 
For DFS startup testing, the important item is the <code>DFS</code> flag. If the same frequency range starts faster after removing <code>DFS</code>, then DFS/radar handling was part of the delay.
 
Changing transmit power alone is not a direct DFS test.
 
=== US Regulatory Block ===
 
<pre>
country US: DFS-FCC
country US: DFS-FCC
# S1G Channel 1-3
# S1G Channel 1-3
Line 75: Line 38:
# channels 1-6 EIRP=40dBm(43dBm peak)
# channels 1-6 EIRP=40dBm(43dBm peak)
(57240 - 71000 @ 2160), (40)
(57240 - 71000 @ 2160), (40)
</pre>
</pre>...to something similar to what's in the below "Try This..." Section
 
then;
 
* make clean && \
* make regulatory.db && \
* scp regulatory.db root@WhatEverIPAddressOfOpenWRTDevice /lib/firmware/regulatory.db (SCP will need to be installed on OpenWRT device)
 
=== Just So It's Known ===
<code>DFS</code> Dynamic Frequency Selection. The radio must check for radar before using that channel as an access point. This can delay wireless startup.
 
<code>AUTO-BW</code> automatic bandwidth handling inside the regulatory code. It helps determine whether wider channels are allowed across compatible frequency ranges. It does not mean automatic channel selection.
 
<code>NO-OUTDOOR</code> outdoor use is not allowed for that frequency range.
 
<code>NO-IR</code> No Initiating Radiation. The device is not allowed to initiate transmissions on that range. In practice, this can prevent access point mode or active scanning.
 
<code>NO-OFDM</code> Orthogonal Frequency-Division Multiplexing is not allowed. This is mostly relevant to special legacy restrictions.
 
<code>wmmrule=ETSI</code> ETSI Wireless Multimedia parameters. This affects Quality of Service / contention behavior, not DFS startup delay.
 
=== Try This (For Boot Speed Testing ONLY!  Transmit Power ONLY changed to verify if OpenWRT does indeed read new config) ===
<syntaxhighlight lang="text">
country US: DFS-FCC
# S1G Channel 1-3
(902 - 904 @ 2), (33)
# S1G Channel 5-35
(904 - 920 @ 16), (33)
# S1G Channel 37-51
(920 - 928 @ 8), (33)
(2400 - 2472 @ 40), (33)
# 5.15 ~ 5.25 GHz: 30 dBm for master mode, 23 dBm for clients
(5150 - 5250 @ 80), (33), AUTO-BW
(5250 - 5350 @ 80), (33), AUTO-BW
# This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
# Since 5725 ~ 5730 MHz belongs to the next range which has looser
# requirements, we can extend the range by 5 MHz to make the kernel
# happy and be able to use channel 144.
(5470 - 5730 @ 160), (33), AUTO-BW
(5730 - 5850 @ 80), (33), AUTO-BW
# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
(5850 - 5895 @ 40), (33), AUTO-BW
# 6g band
# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6ghz-band
(5925 - 7125 @ 320), (12), AUTO-BW
# 60g band
# reference: section IV-D https://docs.fcc.gov/public/attachments/FCC-16-89A1.pdf
# channels 1-6 EIRP=40dBm(43dBm peak)
(57240 - 71000 @ 2160), (40)
</syntaxhighlight>See?  Now change it back to be legal.

Latest revision as of 02:59, 29 June 2026

...wondering about long boot times for OpenWRT 25.x.y on a WRT32X or similar if a WiFi Channel is set to "Auto"?

Could it really be the fault of a WiFi setting causing long boot times? Believe it or not: YES!

This Needs to be Done on a Full Linux System with Make, Python, etc.

wget https://www.kernel.org/pub/software/network/wireless-regdb/wireless-regdb-2026.03.18.tar.xz

Then; tar -xf wireless-regdb-2026.03.18.tar.xz

Go into the directory: cd wireless-regdb-2026.03.18

Edit the db.txt File (ORIGINAL "US Section" is below);

country US: DFS-FCC
	# S1G Channel 1-3
	(902 - 904 @ 2), (30)
	# S1G Channel 5-35
	(904 - 920 @ 16), (30)
	# S1G Channel 37-51
	(920 - 928 @ 8), (30)
	(2400 - 2472 @ 40), (30)
	# 5.15 ~ 5.25 GHz: 30 dBm for master mode, 23 dBm for clients
	(5150 - 5250 @ 80), (23), AUTO-BW
	(5250 - 5350 @ 80), (24), DFS, AUTO-BW
	# This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
	# Since 5725 ~ 5730 MHz belongs to the next range which has looser
	# requirements, we can extend the range by 5 MHz to make the kernel
	# happy and be able to use channel 144.
	(5470 - 5730 @ 160), (24), DFS
	(5730 - 5850 @ 80), (31), AUTO-BW
	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
	(5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
	# 6g band
	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6ghz-band
	(5925 - 7125 @ 320), (12), NO-OUTDOOR, NO-IR
	# 60g band
	# reference: section IV-D https://docs.fcc.gov/public/attachments/FCC-16-89A1.pdf
	# channels 1-6 EIRP=40dBm(43dBm peak)
	(57240 - 71000 @ 2160), (40)

...to something similar to what's in the below "Try This..." Section

then;

  • make clean && \
  • make regulatory.db && \
  • scp regulatory.db root@WhatEverIPAddressOfOpenWRTDevice /lib/firmware/regulatory.db (SCP will need to be installed on OpenWRT device)

Just So It's Known

DFS Dynamic Frequency Selection. The radio must check for radar before using that channel as an access point. This can delay wireless startup.

AUTO-BW automatic bandwidth handling inside the regulatory code. It helps determine whether wider channels are allowed across compatible frequency ranges. It does not mean automatic channel selection.

NO-OUTDOOR outdoor use is not allowed for that frequency range.

NO-IR No Initiating Radiation. The device is not allowed to initiate transmissions on that range. In practice, this can prevent access point mode or active scanning.

NO-OFDM Orthogonal Frequency-Division Multiplexing is not allowed. This is mostly relevant to special legacy restrictions.

wmmrule=ETSI ETSI Wireless Multimedia parameters. This affects Quality of Service / contention behavior, not DFS startup delay.

Try This (For Boot Speed Testing ONLY! Transmit Power ONLY changed to verify if OpenWRT does indeed read new config)

country US: DFS-FCC
	# S1G Channel 1-3
	(902 - 904 @ 2), (33)
	# S1G Channel 5-35
	(904 - 920 @ 16), (33)
	# S1G Channel 37-51
	(920 - 928 @ 8), (33)
	(2400 - 2472 @ 40), (33)
	# 5.15 ~ 5.25 GHz: 30 dBm for master mode, 23 dBm for clients
	(5150 - 5250 @ 80), (33), AUTO-BW
	(5250 - 5350 @ 80), (33), AUTO-BW
	# This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
	# Since 5725 ~ 5730 MHz belongs to the next range which has looser
	# requirements, we can extend the range by 5 MHz to make the kernel
	# happy and be able to use channel 144.
	(5470 - 5730 @ 160), (33), AUTO-BW
	(5730 - 5850 @ 80), (33), AUTO-BW
	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
	(5850 - 5895 @ 40), (33), AUTO-BW
	# 6g band
	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6ghz-band
	(5925 - 7125 @ 320), (12), AUTO-BW
	# 60g band
	# reference: section IV-D https://docs.fcc.gov/public/attachments/FCC-16-89A1.pdf
	# channels 1-6 EIRP=40dBm(43dBm peak)
	(57240 - 71000 @ 2160), (40)

See? Now change it back to be legal.

Retrieved from "https://wiki.terrabase.info/index.php?title=OpenWRT_Boot_Times_Affected_by_WiFi&oldid=2269"