[HECnet] DECnet for Linux

One more note: In the last longterm 3.x.y kernel, 3.18.92, sock_alloc_send_skb() sets the errcode to ENOBUFS even when the sk_buff is allocated successfully. This causes sendmsg() to stop with "No buffer space available". That is easy to fix in dn_alloc_send_pskb(). On Mon, Jan 15, 2018 at 09:43:53PM +0100, Erik Olofsen wrote: >Some more notes on this: > >The problem of accessing a Linux machine seems to be related to >the standard mtu of 1500 of a network interface. > >Reducing the maximum packet size to 576 helps; > >https://sourceforge.net/p/linux-decnet/mailman/message/2395733/ > >This can be done using ifconfig or using 576 instead of dst_mtu() >in dn_current_mss() af_decnet.c of the kernel module source. > >tcpdump shows that a large data packet is one byte too long. >Perhaps this occurs because the pad byte in the header is not counted >in dn_mss_from_pmtu() in af_decnet.c; with an additional mtu-- >this seems to be fixed. > >Kernel warnings related to dst.h; > >https://www.spinics.net/lists/netdev/msg225996.html > >indeed disappear by using dst_metric_raw at two places. > >The above was tested with kernel 3.10.17, and can be tested >with http://mim.update.uu.se/hecnet and nodename RULLFL. > >dntype mim::nodenames.dat works very well on a real machine; why >it doesn't work very well with the virtual machine is not really >solved yet... > > >On Wed, Jan 03, 2018 at 04:44:54PM +0100, Johnny Billquist wrote: >>On 2018-01-03 16:02, Erik Olofsen wrote: >>>On a virtual machine with lubuntu 12.04, kernel 3.2.0, I have >>>DECnet for Linux V.2.5.68s working, with dnprogs version 2.65. >>>It is node RULLFL. >>> >>>The daemons and utilities use decnet.conf with node information, >>>so something useful would be to create it from mim::nodenames.dat. >>> >>>On a VAX, TYPEing it works well, but on the Linux machine, dntype >>>hangs after giving parts of the file; dndir mim:: works well. >>> >>>Does anyone have dntype mim::nodenames.dat working properly (with >>>perhaps different versions of the above)? >> >>I can't help, but I can report that trying to read a file from a Linux >>machine on MIM also hangs after a while. >>A big problem with the DECnet/Linux implementation is that the developers >>only ever tested against VMS, and nothing else. >> >>I've known for ages that it does not play well with RSX. But I do not want >>to dig into the Linux implementation. >> >>(The Linux DAP claims to be a VMS system, by the way, which is probably also >>not a good idea. Better if it had claimed to be some Unix derivative.) >> >> Johnny >> >>-- >>Johnny Billquist || "I'm on a bus >> || on a psychedelic trip >>email: bqt at softjar.se || Reading murder books >>pdp is alive! || tryin' to stay hip" - B. Idol