feedrate interpretation for moves involving both, primary axes (XYZ) and secondary linear axes (UVW) differs from LinuxCNC

[DerAndere1]

NIST RS274NGC interpreter was open sourced as LinuxCNC. While the NIST RS274NGC interpreter - version 3 does not support axes UVW, these axes were added in LinuxCNC.
LinuxCNC has this logic:

    if(dx || dy || dz)
        out.dtot = sqrt(dx * dx + dy * dy + dz * dz);
    else
        out.dtot = sqrt(du * du + dv * dv + dw * dw);

    if (out.tmax <= 0.0) {
        out.vel = canon.linearFeedRate;
    } else {
        out.vel = out.dtot / out.tmax;
    }

(see https://github.com/LinuxCNC/linuxcnc/blob/8a9665315cd96e9da24e08a0885b9a3686f1e7aa/src/emc/task/emccanon.cc#L795-L804)

But you have

g2/g2core/plan_line.cpp

Lines 563 to 564 in 28e7286

	#if (AXES == 9)
	feed_time = sqrt(axis_square[AXIS_X] + axis_square[AXIS_Y] + axis_square[AXIS_Z] + axis_square[AXIS_U] + axis_square[AXIS_V] + axis_square[AXIS_W]) / bf->gm.feed_rate;