can_ioctl_data_s is in a 32-bit union. https://github.com/apache/nuttx/blob/40c6af6dec0d769ac57f69e89709f9d6310ee0c6/include/net/if.h#L299 Making it 64-bit would break that union.
Hence back then it was chosen to use kHz instead. Yours sincerely, Peter van der Perk -----Original Message----- From: Carlos Sanchez <carlossanc...@geotab.com.INVALID> Sent: Wednesday, April 16, 2025 9:37 AM To: dev@nuttx.apache.org Subject: CAN ioctl units (WAS: socketcan ioctl(...SIOCSCANBITRATE...) brings the interface up) > > I was going to propose another global CAN change, removing the 1000 > > factor from bitrate thus making bitrate calls use units in Hz > > instead of kHz, so we can discuss that and (if agreed) I make the > > change on the same PR to avoid creating so a tiny one. > What's the unit used on Linux? we need to align the interface with Linux. Units in linux are Hz, according to https://docs.kernel.org/networking/can.html#the-can-network-device-driver-interface One problem with using kHz is Single Wire Can (SAE J2411) uses bitrates of 33333 bps (83333 bps in high speed mode) so representing this in kbps causes a timing error which can be significant in some cases. The change would require modifying arbi_bitrate and data_bitrate fields on struct can_ioctl_data_s from uint16_t to uint32_t, otherwise usual bitrates cannot be represented. Carlos
