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From: Andrew Lunn <andrew@lunn.ch>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: "Jakub Kicinski" <kuba@kernel.org>,
	davem@davemloft.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
	"Eric Dumazet" <edumazet@google.com>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Russell King" <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	"Christophe Leroy" <christophe.leroy@csgroup.eu>,
	"Herve Codina" <herve.codina@bootlin.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Vladimir Oltean" <vladimir.oltean@nxp.com>,
	"Köry Maincent" <kory.maincent@bootlin.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Marek Behún" <kabel@kernel.org>,
	"Piergiorgio Beruto" <piergiorgio.beruto@gmail.com>,
	"Oleksij Rempel" <o.rempel@pengutronix.de>,
	"Nicolò Veronese" <nicveronese@gmail.com>,
	"Simon Horman" <horms@kernel.org>
Subject: Re: [PATCH net-next v5 07/13] net: ethtool: Introduce a command to list PHYs on an interface
Date: Thu, 25 Jan 2024 18:10:15 +0100	[thread overview]
Message-ID: <c0d1c08e-e9a7-44d2-bc66-bb8179f5a170@lunn.ch> (raw)
In-Reply-To: <20240125092225.45cdaa09@device-28.home>

> I do face a problem with fixed_phy though now that I've played around
> with it. As fixed_phys share the same global MDIO bus, what can happen
> is that netdevsim-registered PHYs can starve the dummy MDIO bus by
> exhausting all 32 mdio addresses, preventing real interfaces from
> getting their own fixed-phy instance.
> 
> I'll probably register a dedicated mdio bus per netdevsim (or even
> per-phy, so that we can imagine controling the returned register
> values), let's see how it goes.

I can see it being a problem, but how theoretical is it?

Anything using phylink does not need a fixed-link device, its just MAC
drivers making use of phylib. Its also only typically used with MACs
connected to switches, and you tend not to have too many of them on a
machine. And lastly, netdevsim is only really used for testing, and i
guess most tests run either on a desktop or server like machine which
does not have switches, probably does not even make use phylib, or the
tests are run in a VM which does not even have any PHYs, fixed or not.

So i'm wondering how much effort should be put into this, or should
the time be spent on other things?

    Andrew



WARNING: multiple messages have this Message-ID (diff)
From: Andrew Lunn <andrew@lunn.ch>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: "Jakub Kicinski" <kuba@kernel.org>,
	davem@davemloft.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
	"Eric Dumazet" <edumazet@google.com>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Russell King" <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	"Christophe Leroy" <christophe.leroy@csgroup.eu>,
	"Herve Codina" <herve.codina@bootlin.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Vladimir Oltean" <vladimir.oltean@nxp.com>,
	"Köry Maincent" <kory.maincent@bootlin.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Marek Behún" <kabel@kernel.org>,
	"Piergiorgio Beruto" <piergiorgio.beruto@gmail.com>,
	"Oleksij Rempel" <o.rempel@pengutronix.de>,
	"Nicolò Veronese" <nicveronese@gmail.com>,
	"Simon Horman" <horms@kernel.org>
Subject: Re: [PATCH net-next v5 07/13] net: ethtool: Introduce a command to list PHYs on an interface
Date: Thu, 25 Jan 2024 18:10:15 +0100	[thread overview]
Message-ID: <c0d1c08e-e9a7-44d2-bc66-bb8179f5a170@lunn.ch> (raw)
In-Reply-To: <20240125092225.45cdaa09@device-28.home>

> I do face a problem with fixed_phy though now that I've played around
> with it. As fixed_phys share the same global MDIO bus, what can happen
> is that netdevsim-registered PHYs can starve the dummy MDIO bus by
> exhausting all 32 mdio addresses, preventing real interfaces from
> getting their own fixed-phy instance.
> 
> I'll probably register a dedicated mdio bus per netdevsim (or even
> per-phy, so that we can imagine controling the returned register
> values), let's see how it goes.

I can see it being a problem, but how theoretical is it?

Anything using phylink does not need a fixed-link device, its just MAC
drivers making use of phylib. Its also only typically used with MACs
connected to switches, and you tend not to have too many of them on a
machine. And lastly, netdevsim is only really used for testing, and i
guess most tests run either on a desktop or server like machine which
does not have switches, probably does not even make use phylib, or the
tests are run in a VM which does not even have any PHYs, fixed or not.

So i'm wondering how much effort should be put into this, or should
the time be spent on other things?

    Andrew



_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2024-01-25 17:10 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-21 18:00 [PATCH net-next v5 00/13] Introduce PHY listing and link_topology tracking Maxime Chevallier
2023-12-21 18:00 ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 01/13] net: phy: Introduce ethernet link topology representation Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2024-01-04 23:12   ` Jakub Kicinski
2024-01-04 23:12     ` Jakub Kicinski
2024-01-05  2:21     ` Andrew Lunn
2024-01-05  2:21       ` Andrew Lunn
2024-01-05  9:29     ` Maxime Chevallier
2024-01-05  9:29       ` Maxime Chevallier
2024-01-05 15:34       ` Jakub Kicinski
2024-01-05 15:34         ` Jakub Kicinski
2023-12-21 18:00 ` [PATCH net-next v5 02/13] net: sfp: pass the phy_device when disconnecting an sfp module's PHY Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2024-01-03 15:20   ` Russell King (Oracle)
2024-01-03 15:20     ` Russell King (Oracle)
2024-01-03 17:45     ` Maxime Chevallier
2024-01-03 17:45       ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 03/13] net: phy: add helpers to handle sfp phy connect/disconnect Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 04/13] net: sfp: Add helper to return the SFP bus name Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 05/13] net: ethtool: Allow passing a phy index for some commands Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2024-01-04 23:15   ` Jakub Kicinski
2024-01-04 23:15     ` Jakub Kicinski
2024-01-05  9:30     ` Maxime Chevallier
2024-01-05  9:30       ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 06/13] netlink: specs: add phy-index as a header parameter Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 07/13] net: ethtool: Introduce a command to list PHYs on an interface Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2024-01-04 23:34   ` Jakub Kicinski
2024-01-04 23:34     ` Jakub Kicinski
2024-01-05  9:43     ` Maxime Chevallier
2024-01-05  9:43       ` Maxime Chevallier
2024-01-05 13:17       ` Andrew Lunn
2024-01-05 13:17         ` Andrew Lunn
2024-01-24 13:50         ` Maxime Chevallier
2024-01-24 13:50           ` Maxime Chevallier
2024-01-24 16:54           ` Andrew Lunn
2024-01-24 16:54             ` Andrew Lunn
2024-01-25  8:22             ` Maxime Chevallier
2024-01-25  8:22               ` Maxime Chevallier
2024-01-25 17:10               ` Andrew Lunn [this message]
2024-01-25 17:10                 ` Andrew Lunn
2024-01-05 15:39       ` Jakub Kicinski
2024-01-05 15:39         ` Jakub Kicinski
2023-12-21 18:00 ` [PATCH net-next v5 08/13] netlink: specs: add ethnl PHY_GET command set Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 09/13] net: ethtool: plca: Target the command to the requested PHY Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 10/13] net: ethtool: pse-pd: " Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 11/13] net: ethtool: cable-test: " Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 12/13] net: ethtool: strset: Allow querying phy stats by index Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2023-12-21 18:00 ` [PATCH net-next v5 13/13] Documentation: networking: document phy_link_topology Maxime Chevallier
2023-12-21 18:00   ` Maxime Chevallier
2024-01-01 18:40 ` [PATCH net-next v5 00/13] Introduce PHY listing and link_topology tracking patchwork-bot+netdevbpf
2024-01-01 18:40   ` patchwork-bot+netdevbpf
2024-01-02 11:57   ` Russell King (Oracle)
2024-01-02 11:57     ` Russell King (Oracle)
2024-01-02 18:51     ` Jakub Kicinski
2024-01-02 18:51       ` Jakub Kicinski
2024-01-03 14:33       ` Maxime Chevallier
2024-01-03 14:33         ` Maxime Chevallier
2024-01-04 23:47         ` Jakub Kicinski
2024-01-04 23:47           ` Jakub Kicinski
2024-01-04 23:50           ` Florian Fainelli
2024-01-04 23:50             ` Florian Fainelli
2024-01-05  0:56             ` Jakub Kicinski
2024-01-05  0:56               ` Jakub Kicinski
2024-01-05  9:00               ` Maxime Chevallier
2024-01-05  9:00                 ` Maxime Chevallier

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