linux-kernel - Re: [PATCH bpf-next 1/1] selftests/bpf: Enable Tx hwtstamp in xdp_hw

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Message-ID: <Z1H-L3BkxnjVr5Qy@mini-arch>
Date: Thu, 5 Dec 2024 11:25:35 -0800
From: Stanislav Fomichev <stfomichev@...il.com>
To: "Song, Yoong Siang" <yoong.siang.song@...el.com>
Cc: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	"David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Eduard Zingerman <eddyz87@...il.com>,
	Mykola Lysenko <mykolal@...com>,
	Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	Shuah Khan <shuah@...nel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next 1/1] selftests/bpf: Enable Tx hwtstamp in
 xdp_hw_metadata

On 12/05, Song, Yoong Siang wrote:
> On Wednesday, December 4, 2024 11:49 PM, Stanislav Fomichev <stfomichev@...il.com> wrote:
> >On 12/04, Song Yoong Siang wrote:
> >> Set tx_type to HWTSTAMP_TX_ON to enable hardware timestamping for all
> >> outgoing packets.
> >>
> >> Besides, set XDP_UMEM_TX_METADATA_LEN flag to reserve tx_metadata_len bytes
> >> of per-chunk metadata.
> >
> >XDP_UMEM_TX_METADATA_LEN is missing after d5e726d9143c ("xsk: Require
> >XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len"), so that make
> >sense. Maybe add a fixes tag?
> >
> 
> Sure. I will add the fixes tag and submit with "PATCH bpf" prefix
> in next version.
> 
> >And I don't see mlx5 looking at HWTSTAMP_TX anywhere in the drivers,
> >so I'm assuming that's why I didn't need HWTSTAMP_TX_ON during my tests..
> >Which device are you testing against? I do see some hwts_tx_en
> >checks in the stfmmac at least... Can you add these details to the
> >commit message and respin?
> >
> 
> I am testing on stmmac and igc drivers.
> You are right, stmmac needs it for hwts_tx_en check.
> Besides, igc needs it to set IGC_RING_FLAG_TX_HWTSTAMP flag.
> 
> Without this patch, user will need to manually enable tx hwts using
> command: sudo hwstamp_ctl -i eth0 -t 1 -r 1
> after start xdp_hw_metadata.
> 
> Therefore, adding HWTSTAMP_TX_ON is not a bug fix solution.
> I will separate this as another new patch to "PATCH bpf-next"
> and provide detail in commit message.
> 
> Btw, is mlx5 driver always enable Tx HWTS?

I don't remember doing anything special to enable it. And looking at
the code I also don't see any conditionals on HWTSTAMP_TX_ON.