On Fri, Nov 23, 2012 at 05:46:27PM +0000, Christian Weisgerber wrote: > Stuart Henderson <[email protected]> wrote: > > > This adds an ioctl to retrieve if_hardmtu, and adds code to > > display it via ifconfig hwfeatures. > > I'm worried that our drivers don't set this or that the value doesn't > accurately reflect the capabilities of chip/driver. >
If the driver doesn't set it, if_hardmtu defaults to 1500. I think this should be fine. But the if_hardmtu is really just a guess or a "driver limit", because sometimes the chipset specs lie about the real limit (it is either more or even less) or the if_hardmtu is based on driver buffer sizes like MCLBYTES - ETHER_HDR_LEN - ETHER_CRC_LEN. But this should be fine as well if we just see it as "what the driver manages to use as a hard limit". Reyk
