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Message-ID: <bdc46437131fc41a1e3217099ca9395ca3c63b41.camel@sipsolutions.net>
Subject: Re: [PATCH 2/6] nl80211: add support to advertise driver's EHT
 capabilities
From:   Johannes Berg <johannes@sipsolutions.net>
To:     "Aloka Dixit (QUIC)" <quic_alokad@quicinc.com>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "Vikram Kandukuri (QUIC)" <quic_vikram@quicinc.com>,
        "Jia Ding (QUIC)" <quic_jiad@quicinc.com>,
        "Karthikeyan Periyasamy (QUIC)" <quic_periyasa@quicinc.com>,
        "Muna Sinada (QUIC)" <quic_msinada@quicinc.com>,
        "Sriram R (QUIC)" <quic_srirrama@quicinc.com>,
        "Veerendranath Jakkam (QUIC)" <quic_vjakkam@quicinc.com>,
        Aloka Dixit <alokad@qti.qualcomm.com>
Date:   Thu, 10 Feb 2022 12:17:06 +0100
In-Reply-To: <793a595932ea0adf7a72eeafb6ababdae8e21fc2.camel@sipsolutions.net>
References: <1640163883-12696-1-git-send-email-quic_vjakkam@quicinc.com>
         <1640163883-12696-3-git-send-email-quic_vjakkam@quicinc.com>
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On Thu, 2022-02-10 at 09:26 +0100, Johannes Berg wrote:
> > 
> > Considering that 20MHz-only STA and one that supports other bandwidths will not occur at the same time,
> > instead of a separate field for struct ieee80211_eht_mcs_nss_supp_20mhz_only inside struct ieee80211_eht_mcs_nss_supp, we can use a byte array as we added in here:
> > https://patchwork.kernel.org/project/linux-wireless/patch/1640163883-12696-3-git-send-email-quic_vjakkam@quicinc.com/
> > Instead of length field with dynamic allocation we can have an array of size 9 bytes.
> > 
> 
> We did something like that in our patches:
> 
> https://patchwork.kernel.org/project/linux-wireless/patch/20220204230119.b0eeb527d761.I2413a37c8f7d2d6d638038a3d95360a3fce0114d@changeid/
> https://patchwork.kernel.org/project/linux-wireless/patch/20220204230119.1ee92202ac30.Id30a3ef2844b296efbd5486fe1da9ca36a95c5cf@changeid/
> 
> Not overlapping wastes like 4 bytes of memory, I think I can live with
> that, vs. the extra complexity? If you overlap you need another bit to
> indicate which one you're using ...
> 

OTOH, that means we need to unwrap it in userspace, which is also
strange ... So yeah I'm changing it to a union.

johannes