Re: [PATCH net-next v16 02/15] net: ethtool: Introduce ETHTOOL_LINK_MEDIUM_* values

Hi Jakub,

On 19/11/2025 04:15, Jakub Kicinski wrote:

On Thu, 13 Nov 2025 09:14:04 +0100 Maxime Chevallier wrote:

quoted

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index c2d8b4ec62eb..ad2b5ed9522b 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h

@@ -216,13 +216,26 @@ static inline u8 *ethtool_rxfh_context_key(struct ethtool_rxfh_context *ctx)
 void ethtool_rxfh_context_lost(struct net_device *dev, u32 context_id);
 
 struct link_mode_info {
-	int                             speed;
-	u8                              lanes;
-	u8                              duplex;
+	int	speed;
+	u8	lanes;
+	u8	min_pairs;
+	u8	pairs;
+	u8	duplex;
+	u16	mediums;
 };
 
 extern const struct link_mode_info link_mode_params[];
 
+extern const char ethtool_link_medium_names[][ETH_GSTRING_LEN];
+
+static inline const char *phy_mediums(enum ethtool_link_medium medium)
+{
+	if (medium >= __ETHTOOL_LINK_MEDIUM_LAST)
+		return "unknown";
+
+	return ethtool_link_medium_names[medium];
+}

Will this function be called by a lot of drivers? Would be great to
find a more suitable place for it, ethtool.h is included by thousands
of objects :(

I expect this to be mostly used by the current DT parsing code, as well
as a few print statements in the core. So indeed let's move this
somewhere more specific.

quoted

 /* declare a link mode bitmap */
 #define __ETHTOOL_DECLARE_LINK_MODE_MASK(name)		\
 	DECLARE_BITMAP(name, __ETHTOOL_LINK_MODE_MASK_NBITS)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 8bd5ea5469d9..6ed235053aed 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h

@@ -2587,4 +2587,24 @@ enum phy_upstream {
 	PHY_UPSTREAM_PHY,
 };
 
+enum ethtool_link_medium {
+	ETHTOOL_LINK_MEDIUM_BASET = 0,
+	ETHTOOL_LINK_MEDIUM_BASEK,
+	ETHTOOL_LINK_MEDIUM_BASES,
+	ETHTOOL_LINK_MEDIUM_BASEC,
+	ETHTOOL_LINK_MEDIUM_BASEL,
+	ETHTOOL_LINK_MEDIUM_BASED,
+	ETHTOOL_LINK_MEDIUM_BASEE,
+	ETHTOOL_LINK_MEDIUM_BASEF,
+	ETHTOOL_LINK_MEDIUM_BASEV,
+	ETHTOOL_LINK_MEDIUM_BASEMLD,
+	ETHTOOL_LINK_MEDIUM_NONE,
+
+	__ETHTOOL_LINK_MEDIUM_LAST,
+};

Why is this in uAPI? I'd have expected it to either exist in the YAML
spec if there's a new uAPI that needs it, or in kernel headers.
Let's move it out for now to be safe, we can always move it in.

I originally planned to report that in linkmodes et.al. but changed my
mind, let me move that out as well.

quoted

+#define ETHTOOL_MEDIUM_FIBER_BITS (BIT(ETHTOOL_LINK_MEDIUM_BASES) | \
+				   BIT(ETHTOOL_LINK_MEDIUM_BASEL) | \
+				   BIT(ETHTOOL_LINK_MEDIUM_BASEF))

Ditto.

Thanks for taking a look,

Maxime