[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