From: Stefan Sperling <stsp@stsp.name>
Subject: Re: sys/iwx: increase maximal VHT A-MPDU from 64K to 1024K
To: tech@openbsd.org
Date: Mon, 30 Mar 2026 18:39:22 +0200

On Mon, Mar 30, 2026 at 06:06:45PM +0200, Kirill A. Korinsky wrote:
> tech@,
> 
> I'd like to increase the maximum VHT A-MPDU length from 64K to 1024K.
> 
> Tested on AX201.
> 
> In my testing with iperf -P 16 test with -R, it brings me to 587 / 576 mbits
> with peak ~622; and without -R to 457 / 454.
> 
> I also double read Linux's iwlwifi driver and it reads safe to switch.
> 
> Ok?

Worth a try. ok stsp@

> Index: sys/dev/pci/if_iwx.c
> ===================================================================
> RCS file: /home/cvs/src/sys/dev/pci/if_iwx.c,v
> diff -u -p -r1.226 if_iwx.c
> --- sys/dev/pci/if_iwx.c	29 Mar 2026 21:17:50 -0000	1.226
> +++ sys/dev/pci/if_iwx.c	30 Mar 2026 09:13:26 -0000
> @@ -6691,7 +6691,7 @@ iwx_add_sta_cmd(struct iwx_softc *sc, st
>  	struct iwx_add_sta_cmd add_sta_cmd;
>  	int err;
>  	uint32_t status, aggsize;
> -	const uint32_t max_aggsize = (IWX_STA_FLG_MAX_AGG_SIZE_64K >>
> +	const uint32_t max_aggsize = (IWX_STA_FLG_MAX_AGG_SIZE_1024K >>
>  		    IWX_STA_FLG_MAX_AGG_SIZE_SHIFT);
>  	struct ieee80211com *ic = &sc->sc_ic;
>  
> @@ -12470,7 +12470,7 @@ iwx_attach(struct device *parent, struct
>  	ic->ic_ampdu_params = (IEEE80211_AMPDU_PARAM_SS_4 | 0x3 /* 64k */);
>  
>  	ic->ic_vhtcaps = IEEE80211_VHTCAP_MAX_MPDU_LENGTH_3895 |
> -	    (IEEE80211_VHTCAP_MAX_AMPDU_LEN_64K <<
> +	    (IEEE80211_VHTCAP_MAX_AMPDU_LEN_1024K <<
>  	    IEEE80211_VHTCAP_MAX_AMPDU_LEN_SHIFT) |
>  	    (IEEE80211_VHTCAP_CHAN_WIDTH_160 <<
>  		IEEE80211_VHTCAP_CHAN_WIDTH_SHIFT) |
> 
> 
> -- 
> wbr, Kirill
> 
>