On 22 November 2017 at 11:25, Peter Corlett via cctalk <cctalk@classiccmp.org> wrote: > On Tue, Nov 21, 2017 at 08:15:00PM +0100, Liam Proven via cctalk wrote: > [...] >> A file-based virus could escape _if_ the VM had access to the host >> filesystem. But mine don't, partly because it's moderately hard, partly >> because it takes a _ton_ of RAM in DOS terms. > > Not really: QEMU can be configured to add a Virtio device, which exposes a > host > filesystem via 9P (the Plan 9 filesystem protocol). A DOS device driver for > that would be of comparable complexity to a CD-ROM driver.
Which itself takes a ton of RAM, in MS-DOS terms. So far, trying VMware Player and VirtualBox, you only seem to get about 48 kB of so of usable UMBs, if you want a page frame as well. CD support takes, well, about that. Circa 35 kB or so. Network support is about 100 kB of RAM -- a hell of a lot for DOS. Back then, the fact that the Netware client could run partially in XMS or EMS was a big competitive advantage. The MS client was lardy, and that was with efficient little protocols like NetBEUI. Add something a bit chunkier like IPX/SPX or DECnet, and it became basically impossible to keep the whole thing from eating a significant chunk of conventional memory too. TCP/IP basically postdates the MS-DOS era, in PC terms, and it's Bloaty McBloatface. Couple that with needing SMB/CIFS support, and you can be looking at something horrendous like 150 kB of RAM. And you want 9p?! I mean, be my guest, go implement it, but to talk to VBox or VMware, you need CIFS. I've tried QEMU and KVM for work, just before I was off sick. My reaction is roughly that of Ford Prefect to Vogon poetry. It might be OK if you want a server hypervisor, which I don't, personally. But then, earlier this year, my reaction to modern server VMware was broadly similar. Horrified incredulity and appalled revulsion. Now I have it working, I concede, it actually _works_ quite well. I can run a bunch of VMs with a total of about 18-20GB of allocated RAM, concurrently, on a host machine with 12GB of RAM, and it _works_, and amazingly it's quick. (Of course this is a play/text box, and they're all unloaded.) But setup... *Screams and writhes* KVM? Well, it's every big as unpleasant or more so, but it's agonizing in a Unixy way, which is at least more familiar, so through the suffering and the tears, I could just about see enough to get it working. But only someone who thinks that Emacs or Vi are usable editors could think this was an appealing virtualisation solution. Did I mention my more or less complete and utter loathing for C21 computing? Why do you think I'm playing with MS-DOS again after 20y? -- Liam Proven • Profile: https://about.me/liamproven Email: lpro...@cix.co.uk • Google Mail/Talk/Plus: lpro...@gmail.com Twitter/Facebook/Flickr: lproven • Skype/LinkedIn/AIM/Yahoo: liamproven UK: +44 7939-087884 • ČR/WhatsApp/Telegram/Signal: +420 702 829 053