Hi On +2020-07-07 16:40:21 -0400, Christopher Lemmer Webber wrote: > In commit 5379392731b52eef22b4936637eb592b93e04318, the following change > was introduced: > > modified gnu/system/vm.scm > @@ -941,6 +941,7 @@ with '-virtfs' options for the host file systems listed > in SHARED-FS." > '()) > > "-no-reboot" > + "-nic" "user,model=virtio-net-pci" > "-object" "rng-random,filename=/dev/urandom,id=guixsd-vm-rng" > "-device" "virtio-rng-pci,rng=guixsd-vm-rng" > > Unfortunately, this means that in our docs where we suggest doing the > following: > > `guix system vm config.scm` -nic > user,model=virtio-net-pci,hostfwd=tcp::10022-:22 > > Since we now provide our own similar "-nic" field this creates a > *second* network interface at the same address and there is a race as in > terms of which handles connections. Depending on the race result, > connections to the forwarded port may hang indefinitely. > > Ironically, this regression was introduced to solve another regression! > From the commit message: > > This fixes a regression introduced in > 8e53fe2b91d2776bc1529e7b34967c8f1d9edc32 > where 'guix system vm' would no longer be using virtio. >
This reminds a bit of doctors prescribing powerful medicine with side-effect so bad that they have to prescribe a medicine for that, which in turn has side-effects, in what I think is called prescription cascading, and people wind up on 25 pills a day. "First, do no harm." :) I wouldn't say anything, except ISTM your fix on top of a fix is not the first to remind me of cascading :) > What's the right solution? One could be that "guix system vm" itself > could take an argument that sets up port forwarding in the generated > shell script. Eg: > > guix system vm config.scm --hostfwd=tcp::10022-:22 --hostfwd=tcp::8888-:80 > > kind of ugly, but it could work. WDYT? > > - Chris > > > I'm not saying your solution is bad, I'm just saying cascading fixes may be a symptom to diagnose, in case it indicates something like bad mutations involving bad genes that will compromise the health of the guix ecology. How is a "fix" judged with respect to the big picture? Is there a higher level layered[1] design for the use of guix, like e.g. [2] which a proposed fix might violate and therefore should be rejected, even though it makes something "work"? Well, it's probably in an old paper by Ludo in some form, but I wonder what concepts of layering guix developers are consciously using when putting stuff between the declarations at the top and the images at the bottom. [1] https://en.wikipedia.org/wiki/Abstraction_layer [2] https://en.wikipedia.org/wiki/OSI_model -- Regards, Bengt Richter
