[PATCH] Add an option to set secondary channel in hostapd conf

Arnout Vandecappelle arnout at mind.be
Thu Apr 8 12:51:12 BST 2021

On 26/02/2021 22:16, Jouni Malinen wrote:
> On Thu, Feb 25, 2021 at 04:06:17PM +0200, Orr Mazor wrote:
>> Usefull in case we want to specify the secondary channel
>> or in case we want to be on 20mghz with 40mghz capabilities.
>> It is possible in chan_switch to set secondary channel,
>> however it was not possible to do so when hostapd start.
>> This commit adds this option.
> Can you please clarify how this proposed new parameter differs from the
> existing ht_capab=[HT40+], ht_capab=[HT40-], and ht_capab=[HT40+][HT40-]
> options?

 As far as I understand, the goal is to be able to specify the starting
secondary channel in case ht_capab=[HT40+][HT40-] just like it's possible to
specify it in the chan_switch command with the sec_channel_offset parameter.

 However, I guess that's just a misunderstanding of what ht_capab is doing in
that case. AFAIU, ht_capab=[HT40+] gives the HT40 capability and sets the
starting secondary channel to +1, but subsequent channel switches can still set
it to -1.

 So I think this patch is indeed not needed, and instead it's just a matter of
setting either [HT40+] or [HT40-] in the configuration file, and not both.

 Of course this way of specifying the secondary channel is fairly warty, but it
is what it is :-)


> Please also note that the IEEE 802.11 standard has mandatory
> requirements for 40 MHz co-existence on when the primary and secondary
> channels have to be switched and I'm unlikely to accept changes
> that would allow the user to bypass those requirements.

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