qemu: experimental support for S390X

[AkihiroSuda]

Supporting S390X is useful for testing a program with big-endian.

[jandubois]

How do you run this? I tried l start --tty=false --arch s390x (on macOS 15.3.1 on M1) and get this error in ha.stderr.log:

{"level":"debug","msg":"qemu[stderr]: qemu-system-s390x: -netdev user,id=net0,net=192.168.5.0/24,dhcpstart=192.168.5.15,hostfwd=tcp:127.0.0.1:60022-:22: Could not set up host forwarding rule 'tcp:127.0.0.1:60022-:22'","time":"2025-03-08T22:29:56-08:00"}
{"level":"info","msg":"Driver stopped due to error: \"exit status 1\"","time":"2025-03-08T22:29:56-08:00"}

[afbjorklund]

I know that there were some people fighting hard to keep both ppc64le and s390x in Kubernetes (and minikube), but most of the time it was either untested or (possibly) run only in emulation. So many wanted it to be removed, therefore.

ALL_ARCH = amd64 arm arm64 ppc64le s390x

Think I had some branch that was able to run them (that I since deleted), there were some tweaks that were needed to the startup parameters and what not. But it seems like there will be a rather narrow audience of these, similar to arm32?

• Running minikube on IBM (s390x, ppc64le), use cases kubernetes/minikube#6798
• minikube start fails with podman or kvm2 drivers on s390x kubernetes/minikube#11658

[AkihiroSuda]

How do you run this? I tried l start --tty=false --arch s390x (on macOS 15.3.1 on M1) and get this error in ha.stderr.log:

{"level":"debug","msg":"qemu[stderr]: qemu-system-s390x: -netdev user,id=net0,net=192.168.5.0/24,dhcpstart=192.168.5.15,hostfwd=tcp:127.0.0.1:60022-:22: Could not set up host forwarding rule 'tcp:127.0.0.1:60022-:22'","time":"2025-03-08T22:29:56-08:00"}
{"level":"info","msg":"Driver stopped due to error: \"exit status 1\"","time":"2025-03-08T22:29:56-08:00"}

It just works for me in that way, on macOS 15.3.1 with QEMU 9.2.2 on M4 Max.

Maybe something was occupying the port 60022 ?

[AkihiroSuda]

EL8, 9, and 10 do not seem to support virtio-net-pci on s390x ? 🤔

[   57.518703] cloud-init[967]: ci-info: +++++++++++++++++++++++Net device info++++++++++++++++++++++++                               
[   57.518703] cloud-init[967]: ci-info: +++++++++++++++++++++++Net device info++++++++++++++++++++++++                               
[   57.520356] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+                                                                                                                                                                     
[   57.520356] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+                               
[   57.521522] cloud-init[967]: ci-info: | Device |  Up  |  Address  |    Mask   | Scope | Hw-Address |                                                                                                                                                                     [   57.521522] cloud-init[967]: ci-info: | Device |  Up  |  Address  |    Mask   | Scope | Hw-Address |                                                                                                                                                                     [   57.522383] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+
[   57.522383] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+
[   57.523153] cloud-init[967]: ci-info: |   lo   | True | 127.0.0.1 | 255.0.0.0 |  host |     .      |                               
[   57.523153] cloud-init[967]: ci-info: |   lo   | True | 127.0.0.1 | 255.0.0.0 |  host |     .      |                               
[   57.524012] cloud-init[967]: ci-info: |   lo   | True |  ::1/128  |     .     |  host |     .      |                               
[   57.524012] cloud-init[967]: ci-info: |   lo   | True |  ::1/128  |     .     |  host |     .      |                               
[   57.524941] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+                               
[   57.524941] cloud-init[967]: ci-info: +--------+------+-----------+-----------+-------+------------+ 

Ubuntu 20.04 (kernel 5.4) still works, so this is a matter of the kernel config rather than the version.

[AkihiroSuda]

Updated to use virtio-net-ccw.

The network per se now works, but SSH fails on EL 🤷‍♂️

$ ssh -F ~/.lima/centos-stream-10/ssh.config lima-centos-stream-10
[email protected]: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

[jandubois]

Thanks, LGTM

However, I only tested the default.yaml template.

[AkihiroSuda]

Rebased

[afbjorklund]

I'm not sure about making armv7l experimental*, but s390x changes look OK to me

* "unsupported" is fine, just not very new

[AkihiroSuda]

I'm not sure about making armv7l experimental*, but s390x changes look OK to me

• "unsupported" is fine, just not very new

armv7l has been already experimental: https://lima-vm.io/docs/releases/experimental/