Interesting. It seems that the band-aid I was proposing is already obsolete. We could still use the remaining reserved 16 bits to encode 5 more bits per mask (that is: 53 bits / mask total). But if I understand you, it would allow us to survive only a few months longer, as opposed to a few weeks. One short-term alternative solution I can imagine is the following: /* For example bitmap-based for variable length: */ struct ethtool_link_mode { __u32 cmd; __u8 autoneg :1; __u8 duplex :2; __u16 supported_nbits; __u16 advertising_nbits; __u16 lp_advertising_nbits; __u32 reserved[4]; __u8 masks[0]; }; /* Or simpler, statically limited to 64b / mask, but easier to migrate to for driver authors: */ struct ethtool_link_mode { __u32 cmd; __u8 autoneg :1; __u8 duplex :2; __u64 supported; __u64 advertising; __u64 lp_advertising; __u32 reserved[4]; }; #define ETHTOOL_GLINK_MODE 0x0000004a #define ETHTOOL_SLINK_MODE 0x0000004b struct ethtool_ops { ... int (*get_link_mode)(struct net_device *, struct ethtool_link_mode *); int (*set_link_mode)(struct net_device *, struct ethtool_link_mode *); }; The same thing required for EEE. I am not sure about moving the autoneg and duplex fields into the new struct. Especially the "duplex" field. Then the idea would be to update the ethtool user-space tool to try get/set_link mode when reporting/changing the autoneg/advertising settings. Both will require significant effort from the driver authors. Especially if the variable-length bitmap approach is preferred: - most drivers currently use simple bitwise arithmetic in their code, and that goes far beyond get/set_settings, it is sometimes part of the core driver logic. They will have to migrate to the bitmap API if they want to use the larger bitmaps (note: no change needed if they are happy with <= 32b / mask) - we would have to progressively deprecate the use of #define ADVERTISED_1000baseT_Full in favor of an enum of the bit indices. Any feedback welcome. In the meantime, I am going to propose a v3 of current option with 53 bits / mask. I can also propose a prototype of the scheme described above, please let me know. On Tue, Jan 6, 2015 at 5:56 AM, Amir Vadai <amirv@xxxxxxxxxxxx> wrote: > On 1/6/2015 4:54 AM, David Decotigny wrote: >> This patch series increases the width of the supported/advertising >> ethtool masks from 32 bits to 48. This should allow to breathe for a >> couple more years (or... months?). > Hi, > > Nice work. > What worries me is that it is going to be for weeks more than years or > months... > > Mellanox is about to release next month a driver for a new NIC, with 3 > new speeds * few link modes for each + new link modes for 10G. > It seems that we will need to consume almost all the new bits. > > Amir -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html