[dpdk-dev] [RFC 02/14] virtio: use eth_link_read/write (and bug fix)
Stephen Hemminger
stephen at networkplumber.org
Mon Jul 17 18:01:22 CEST 2017
On Sun, 16 Jul 2017 15:33:26 +0300
Andrew Rybchenko <arybchenko at solarflare.com> wrote:
> > + link.link_autoneg = ETH_LINK_SPEED_FIXED;
>
> As I understand link_autoneg is 1 bit field with boolean semantics. I.e. 0/false - no autoneg, 1/true - autoneg.
> It looks like it has wrong comment:
> uint16_t link_autoneg : 1; /**< ETH_LINK_SPEED_[AUTONEG/FIXED] */
>
> since
> #define ETH_LINK_SPEED_AUTONEG (0 << 0) /**< Autonegotiate (all speeds) */
> #define ETH_LINK_SPEED_FIXED (1 << 0) /**< Disable autoneg (fixed speed) */
>
> whereas
> #define ETH_LINK_FIXED 0 /**< No autonegotiation. */
> #define ETH_LINK_AUTONEG 1 /**< Autonegotiated. */
>
> In general this attempt to introduce bug is the result of wrong comment which is caused by very similar
> defines with opposite values.
Orignal observation was because some drivers (vmxnet3) were setting autoneg = fixed
and others were not. Turns out it makes no difference
since FIXED == 0, the old code and new code have same effect.
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