Hi Frank, > So in that context, in the Debian-based host OS, I've tried sniffing > the traffic coming out of tap0 with tcpdump. And, I'm seeing > something interesting. > In perfect correlation with the DOS guest's DHCP client starting up, > I can see a "packet of all zeroes" every now and then. As if, for > some reason, the DHCP Discovery packets got zero-padded. > A short snippet is attached (packet header, as reported by tcpdump).
> I've tried with or without KVM acceleration in QEMU. > I've tried several variants of the emulated NIC hardware. > I've tried JEMMEX (5.78=latest) with NOVDS and I've tried HimemX.EXE. if experiencing wrong packets, don't use any (J)EMM386. most network cards use DMA to access the buffers to send/receive. in virtual memory environments as created by EMM386, logical addresses and physical addresses are network stacks on top of EMM386 require VDS (Virtual DMA Services) as virtual memory as seen from software are not necessarily identical to physical addresses as seen from the hardware, and must be translated by VDS (virtual DMA Services). while VDS is supported by EMM386 and friends, it's a non-trivial process and might cause problems by itself. living in the QEMU virtual machine doesn't help either ;) in short: when debugging network problems, avoid EMM386/JEMMEX. HIMEM and friends should be fine, though. Tom _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
